Looking for help?

What is ALR / Cortical ERA?
Auditory Late Responses (ALRs) are longer latency components that for most part are generated in higher regions of the auditory CNS, including the auditory cortex. Cortical Evoked Response Audiometry (CERA) refers to the technique of measuring ALRs for the purpose of assessing ones hearing abilities. The responses are typically measured using surface electrodes placed on the scalp of an individual.

Why ALR?
ALR/Cortical ERA is traditionally used to help determine the degree of hearing loss in adult populations. Compared to traditional Auditory Brainstem Responses (ABRs), or behavioral audiometry, ALRs demonstrate audibility at the cortex without the need for the listener to play an active role in the procedure. This is a key advantage in various medico-legal scenarios or in cases where the individual is unable or unwilling to provide accurate behavioral responses to a sound.
Other advantages include the relative robustness of the ALRs to myogenic activity, the high frequency specificity of the tonal stimuli due to their longer duration, and is much closer to the behavioral audiometric pure tone compared to traditional ABR octave wide stimuli, and the ability to calibrate the stimuli according to international standards (BS EN ISO 389 as for pure tone audiometers) and not the standard 389-6 used for Tone burst/Tone pips & Chirps .
The key ALR waveforms observed in CERA are the P1, N1, and P2 responses. The ALR latency typically ranges from 50 – 300 ms and N1-P2 amplitude ranges from 0-20 μV. (see Figure 1, showing P1, N1 and P2 responses to a 2 kHz toneburst stimuli, used to provide a typical threshold recording from the left ear. In this case, hearing sensitivity is shown to be within the normal audiometric range.)

Figure 1 ALR responses Right and Left

How to test
Patient Preparation is very important. Patient arousal and attention state has a significant effect on the amplitudes of the ALR. The ALR waveform changes as a person becomes drowsy or falls asleep. When a patient is asleep the N1 amplitude is smaller and the P2 amplitude is larger. However, when the subject is listening for a change or paying close attention to stimuli the N1 increases in amplitude and in subjects who are not attending to the stimuli, the N1 can become difficult to measure at low intensities (Näätänan and Picton, 1987). The response also habituates quickly, an affect which is more apparent nearer to the threshold of the listener, so it is important to limit the number of stimulus presentations within each ‘run’. Typically, between 15 and 20 presentations might be made per run and a number of successive runs are then merged into a grand average in order to reveal the ALR.
The patient is typically instructed to sit quietly during the procedure, maintaining passive attention for example by reading or watching a close-caption movie with the sound muted. It is not advised to perform ALR and under sedation (Crowley & Colrain, 2004).

What is AMLR?
Auditory Middle-Latency Responses (AMLR) are related to auditory generators of the subcortical regions Na and Pa components at cortical levels. Na is considered the onset of the AMLR and Pa is considered the most robust component of the AMLR.

Why AMLR?
AMLR has the potential to offer a more complete picture of the status of the auditory system and can be used to help determine the degree of hearing loss. The most common neurological use of the AMLR is for the assessment of the functional integrity of the auditory pathway above the level of the brainstem in cases with suspected lesions and for the assessment of nonorganic hearing loss.

Further, AMLR is used in instances of traumatic brain injury, cortical deafness, multiple sclerosis, and cases of central auditory processing disorders.

Young children and infants may not present AMLR even when their auditory and neurological functions are intact, because of their higher sensitivity to stimulus rate. In general AMLR from children younger than 10 years should be interpreted with caution. It is also important to note that prior to the level of interest the auditory function should be examined and working normally, if not this will affect the AMLR results.

The stimuli used for AMLR is similar to the traditional ABR octave wide stimuli.

How to test
Patient Preparation is very important. The patient is instructed to relax and informed about the test procedure prior to testing. AMLR’s are most reliable when the patient is awake and quiet.

During sedation as with natural sleep the ALMR response is not affected.

Electrode Placement:
It is possible to obtain AMLR from with a standard ABR electrode montage. Due to the latency of the AMLR measurement, it is important to pay attention to the PAM muscle artifact, so it is not misinterpreted as an AMLR. To minimize the influence of the PAM muscle, ensure that the patient is calm and relaxed and place the electrodes on the earlobe rather than on the mastoid.

Setting up the Eclipse
The Eclipse comes with a pre-programmed protocol for AMLR testing (license) and is ready to use immediately. Protocols can be created or modified easily to fit your clinic needs. Consult your Eclipse Additional Information to learn how to create or modify a protocol.

Protocol settings:

• An AMLR should be measured using traditional ABR stimuli, such as Toneburst 250Hz – 4kHz, stimuli from the CE-Chirp® LS family or custom wave files at an moderate intensity level.
• For neuro diagnosis a moderate stimuli intensity below 70dB nHL is appropriate.
• For threshold estimation, present stimuli levels as done with traditional ABR threshold testing.
• A slower rate is indicated for younger children or for patients with cortical pathology. Normal rate for adults is below 7.1 stimuli per second.
• Stimuli rates as low as 1 per second or 0.5 per second are required to consistently record the Pb component.

Interpretation of the AMLR result
The AMLR latency ranges from 15-80 ms and amplitude sizes ranges from 0-2uV.

An AMLR threshold recording here using Tone Burst 1kHz for threshold evaluation.

Cochlear implants
The longer latencies of the AMLR separate them from the cochlear implant stimuli artifacts seen under the traditional eABR. Therefore AMLR’s may be used to assess the efficacy of cochlear implants in activating the auditory pathway.

Reporting
Choose the Report Icon .
When complete, choose Save and Exit.

---

References 
Atcherson, S.R. & Kennett, S.W. (2013), Applications of middle and late latency responses, ENT & Audiology news (20)4.

Roeser, R.J., Valente, M., Hosford-Dunn, H. (2007). Audiology Diagnosis, Theime 2^nded

What is Residual Noise?

•  It is the averaged background noise.
  
  How does it Work?
• It is calculated online during the ABR recording by measuring the stability of the averaged waveform.
• The residual noise calculation used for Fmp is the same used for the calculation of Residual Noise - typically in a time window of 10ms.
• The greater the stability, the less noise in the tracing.
• When the Residual Noise level reaches the set criteria, e.g. 40nV for adults and 20nV for children, the residual noise bar turns green with a checkmark.
  

What is Fmp?

• It is a statistical online analysis of the ABR recording from beginning to end.
• The Response Confidence is a statistical confidence of a true detection of a response, by default 99% (Fmp 3.1).
  
  How does it Work?
• It works on the principle of comparing response amplitude to residual noise to provide confidence level or detection rate.
• The underlying analysis considers the ABR recording typically in a time window of 10ms.
• The Fmp ratio between the response amplitude and the residual noise is calculated.
• In a response situation, lower noise or larger response amplitude will drive the Fmp up (indicated by the red line and bar).
• In a no-response situation, the response amplitude will not rise above the residual noise, thus the Fmp value and the Response Confidence will remain low.
  
  What is the benefit of calculating Fmp?
• The calculation provides statistical documentation and support of the findings.
• Acts as a Quality Meter for the waveform.

Benefits of Fmp and Residual Noise

• Low residual noise levels mean there is less noise in the tracing.
• Less noise in the tracing improves confidence when eyeballing the presence or absence of a response.
• It is unlikely that continued averaging with noise levels below 40nV for adults and 20nV for children will result in a response becoming visible, so residual noise may be used as stop criteria in no-response situations.

Clinical benefits

• Improves confidence in a presence or absence of the response.
• Can reduce test time.
• Relies on statistical data not solely on the experience of the user in determining the presence or absence of the response.

---

References 
Don, M. & Elberling, C. (1996). Use of quantitative measures of auditory brain-stem response peak amplitude and residual background noise in the decision to stop averaging. J. Acoust. Soc. Am., 99(1).

Elberling, C. & Don, M. (1984). Quality Estimation of averaged auditory brainstem responses. Scand Audiol., (13) 187-197.

Several things can influence the results obtained during ABR / ABRIS / ASSR testing. In this guide, some hints for improved recordings will be described. All the suggestions listed below can be applied to the ABR, ABRIS and ASSR module.

Skin Preparation and Electrodes

1. Preparing the skin
Always use an abrasive preparation gel (e.g., NuPrep) to ensure that the top layer of skin (epidermis) is cleaned and oil is removed. The skin may become a little red after an appropriate preparation, and you should aim to get impedances below 3kOhm.

Note Be careful not to damage the skin.

Neonates Some clinicians use only alcohol wipes/pads to remove vernix prior to ABR recording on neonates (age 0-3 months). A disinfectant agent such as alcohol can also be used for preparing the skin of neonates.

Preparation instructions: Remove any oil/lotion/vernix from the contact point on patient’s head. Wipe all preparation gel off with an alcohol wipe/pad or a soft dry non-stick cloth (e.g., gauze).

• For sensitive/allergic skin, it may be best to use only a soft dry cloth since alcohol can dry out the skin. If the patient suffers from any known allergies e.g., perfume, pay extra attention to the use of disinfectant agents.
• Since alcohol may take time to dry, impedances may be slightly higher when using alcohol. Make sure that the alcohol is completely dry before applying conductive gel and electrodes.
• Some clinicians prefer not to use alcohol pads/disinfectant agents, but remove the preparation gel with a dry non-stick cloth (e.g., gauze).
• If the patient’s skin is dry or you are obtaining high impedances, apply a small amount of conductive gel/paste to the skin prior to connecting the surface electrode. This will help to rehydrate the skin and to lower impedances.

2. Mounting the electrodes
Always prepare the skin prior to mounting either disposable or reusable electrodes.
Some disposable electrodes are pre-gelled (e.g., PEG15), and no further gel is required.

Note When mounting pre-gelled disposable electrodes (e.g., PEG15), do not press in the middle of the electrode as gel to be dispersed to the adhesive outer edge causing the electrode to loosen from the skin, causing very high impedances during testing.

• Mount the disposable electrode by pressing down around the adhesive outer edge.
• If you gently pull on the electrode a few seconds after application, the electrode should remain tightly adhered to the skin. This should ensure very low impedances (≤ 1kOhm).
• Recommended impedance are below or equal to 3kOhms and balanced (e.g., all electrodes should have similar impedance values within 2kOhms).

Reusable electrodes are expected to have higher impedance than the disposable electrodes.

• For reusable electrodes, it should be possible to achieve impedances in the range of 1-5kOhms.
• Always apply a conductive electrode gel/paste (e.g., 10-20 paste) to all reusable electrodes before mounting.
• Use medical tape (e.g., micropore) to hold the reusable electrode cups in place on the skin.

Lead is sometimes soldered onto the reusable cup electrodes by a hospital to improve their conductivity; producing lower impedances. Reusable electrodes containing lead are not supplied, because of the hazardous nature of lead

Reducing Noise

1. Test Room Parameters
The test room and location of the room can greatly effect ABR recordings.

The following test room parameters should be aimed for:

• A magnetically shielded booth/room (if possible).
• A quiet or soundproofed booth or sound treated room. This ensures the patient can relax without disturbances and the stimulus noise is not masked by background noise.
• Use of a dedicated ground (isolated socket) for the ABR equipment.
• Lights and other equipment not being used should be turned off or unplugged as the patient can work as an antenna and picks up electrical interference from these sources.
• Separate equipment cables to reduce interference (e.g., braid electrode cables, keep electrode cables and transducer cables away from each other).

In some cases, it may be necessary to find another test location if there is too much ambient or electrical noise in the current test room. 
Try moving the test bed within the room. It may be placed unknowingly, adjacent to a wall that has hidden cables and electrical sources.

2. Patient Instructions
The quality of the ABR recordings depends highly on the state of the patient. If the patient is not physically/mentally relaxed, more unstable, noisy recordings will be seen.

Instruct the patient so that:

• They are relaxed and calm.
• Their eyes are closed and that their face and jaw muscles are relaxed.
• They are lying down on a comfortable bed or reclining in a comfortable chair. The duration of an ABR test can be long, so ensure that the patient is as comfortable as possible (use pillows and blankets as needed).
  
  Note An upright sitting position should be avoided due to contracted neck/head muscles.
  
  
• Turn off lights in the test room to avoid electrical interference and to help the patient to relax/go to sleep. Sleeping during recording will provide the lowest noise from the patient, so a sleeping state is preferred if possible.
• Test infants and children during sleep is recommended as they cannot be instructed to or find it difficult to relax for the entire test duration.

It is important to try and use the same test conditions and parameters for each test when comparing results.

3. Set an appropriate rejection level

• A recording cannot be collected if the system rejects the signal.
• Adjust the rejection level to an appropriate level according to the patient and test type. Typically, ABR recordings can be made using a rejection level of 40μV or less when the patient is relaxed and/or sleeping.
• A lower rejection level means a lower amount of noise is recorded during each average. This equates to faster and more accurate recordings.

Changing the rejection level
The rejection level should be increased until the real time EEG signal (top of the screen) is no longer red (indicating rejection). The rejection level used will depend on the patient and the electrical interference in the test room. A black EEG curve indicates that the system is ready to measure.

The higher the rejection level value, the more noise is recorded during each average. Therefore, always use the lowest possible rejection level value, without rejection. The level can be adjusted during a recording, by double clicking on the EEG window (EP15/25 only) and adjusting the input level by dragging the horizontal bars.

If a high rejection setting is needed, check that electrode impedances are sufficiently low and that the patient is relaxed before starting the test. Muscle tension of the face, back or neck due an uncomfortable or incorrect position will disturb the ABR recordings as these muscles are close to the recording site.

4. Use of a Ground
Grounding is crucial for good ABR waves and safe operation. A separate ground dedicated for the ABR equipment should be used. A true ground uses a minimum of three earth rods.

The Eclipse’s power cord contains a ground lead (typically indicated by yellow and green colors), but often the ground at the test site may not be sufficient.

• Always check the wall outlet for a proper ground when establishing an ABR test room. Sometimes the ground lead is found inside the wall outlet, but is not connected to the ground. In these cases where the ground is not connected or even missing, the ABR recordings will be dramatically distorted.
• Electrical interference may appear through the ground lead if the wall outlet used is connected to a shared ground (e.g., other wall outlets with electrical equipment connected share the ground). In this case, a dedicated ground wall outlet for the ABR recording equipment should be established.
• The ABR system cabinet is connected to the ground lead via an internal capacitor. If the ground lead is not connected, the ABR system will pick up electrical noise/interference. This will be seen on the screen as very large harmonic distortion curves completely overlaying/destroying the ABR curves.
• Ground the patient bed if it is made of metal. On the backside of the Eclipse, there is a special ground plug which can be connected to the patient bed.

Check the ground for proper and correct function
Due to High Voltage, only experienced technicians/ properly trained staff must check and change the ground.

To check and verify the ground, various methods can be used.

1. Adedicatedgroundtester.
2. Avoltage/impedancecomparisonfromthewalloutletgroundleadtoatriangleofearthrods.
3. Ground should have max 8ohm, and 0.5V deviation compared to the true ground.
4. A more simple check is to use a Voltage Meter and measure directly from the wall outlet. Please verify these specifications:
   1. The Voltage between Phase (Hot) socket and Zero (Neutral) socket must be a stable 230V for Europe /110V for US (country specific).
   2. Check the Voltage between phase (Hot) socket and Ground socket, 230V for Europe / 110V for US (country specific). The voltage value found in step a, should match the voltage value found in this step (within 5V). If the recorded voltage is much less than the expected voltage (e.g., a voltage reading of 50V for US), the ground is not connected to a true ground, even though you may be able to see the lead in the wall.
   3. Check the Voltage between Zero (Neutral) and Ground. It must be 0V. If the recorded voltage is much less than the expected voltage, the ground is not connected to a true ground, even though you may be able to see the lead in the wall.

Reducing noise in the EP15/25 module

1. Optimizing Settings
Changing the filter settings can reduce excessive environmental electrical interference.

With the EP software, go to File - System setup – Auto Protocols tab.
For 15ms tests (ABR-15), change the high pass filter to “100Hz 12/oct”.

Note Using a filter setting like this may reduce the amplitude in the ABR waveforms. However it may be needed if it is impossible to obtain ABR curves without excessive electrical interference.

Change the stimulus rate so that it isn’t time locked to other electrical interference (e.g., 50/60Hz mains) can reduce noise.

For periodic interferences, use the Minimize Interference option. Small random pauses are inserted between stimulus presentations, minimizing the synchronization with electrical interference. These pauses do not influence latency times or in any other manner, change the behavior of ABRs.

Please refer to the Eclipse Additional Information for more information.

2. Use Insert Headphones
The recording below was carried out using reusable electrodes and headphones. Note the very large spikes before 1ms, especially on the curves at high intensities.

This is an electrical artifact caused by electrical coupling from the headphones to the input circuit when high sound stimuli intensities are used.

To solve this:

• Always use insert earphones.
• If using headphones they must be shielded. A shielded headset will still produce a small artefact using intensities above 90 dB SPL.
• Start the recording window after the artifact.

What is Bayesian Weighting?
Bayesian Weighting is a tool designed to assist the clinician when testing in less than optimal conditions. While giving sweeps with less noise a higher “score”, sweeps with more noise are not given the same level of importance in the overall recording. Each sweep is analysed and not simply accepted ot rejected as with traditional averaging but is given a unique signficance based on its level of noise. Baysian Weighting can be used in all typical ABR testing situations and will be effective when EEG levels vary during recording.

When and why to use Bayesian Weighting?
When

• As Bayesian Weighting does not change the response of a waveform, you may use Bayesian in all typical ABR recording situations

Why

• The optimum use of all data reduces test time.
• More stable recordings, as residual noise will never suddenly rise (and a good waveform deteriorate) during recording, even if patient starts to be uneasy.
• The difficulty of selecting the optimum rejection rate is reduced, as a softer rejection rate can be used without the noisier sweeps contaminating the more quite sweeps.

When is Bayesian Weighting less Relevant?
If the patient does not have a fluctuating EEG during the session: Bayesian weights noisy sweeps less and quite sweeps more. In a situation where all sweeps are the same, they will be weighted equally. This is identical to normal averaging. Hence, there is no difference between recordings with and without Bayesian.

If a very tough rejection level is set: In this case, all noisy sweeps are simply rejected for both Bayesian and non-Bayesian recordings. Only the most quite sweeps are accepted, and you have a situation almost similar to above. With softer rejection criteria (e.g. 80μV) you would benefit from the contributions of the more noisy sweeps in your averaging thus arriving at your desired residual noise level in less time.

If you run long enough to get a low residual noise level
If two waveforms each have 40nV residual noise, then they will look equally clean. It does not matter whether you have used 1.000 or 10.000 sweeps to get there or what type of weighting is used. Weighting will simply get you there faster if the patient has fluctuating EEG during the session. It should be noted that two waveforms each with 40nV residual noise may exhibit minor variations in wave morphology due to e.g. the frequency distribution of the residual noise. This may differ with different test situations, and quite patients tend to provide residual noise with more high frequency content and less low frequency content, which may look nicer to the eye. So keeping the patient as relaxed as possible is still recommended.

---

References
Elberling, C. & Wahlgreen (1985). Estimation of auditory brainstem response, ABR, by means of Bayesian interference. Scand. Audiol (14) 89-96.

What is Neuro Latency Protocol?
The default Neuro Latency protocol is designed to evaluate the integrity of the neurologic system. The changes in response latency between the right and left ear at slow stimulation rates are recorded and compared. The Eclipse offers both markers and performs the calculation between the inter-peak Wave I, III & V latencies (between Left and Right). The purpose of the test is to look for retro cochlear pathology.

How does it Work?
The test is run like a traditional ABR. The clinician tests at a high intensity (ex. 80 or even 90dBHL) with a slow rate (i.e. 11.1Hz). The Wave I, III & V for the tracings is marked with the appropriate markers. After they are marked, interaural wave I, III & V and the intra-aural change is calculated.

An interaural difference of maximum 0.3ms is often used as critical value in clinical practice (Stürzebecher et al., 1985; Olsen et al., 1997). 

---

References
Stürzebecher, E. Kevanishvili Z., Webrs, M., Meyer, E., Schmidt, D. (1985). Interpeak intervals of auditory brainstem response, interaural differences in normal-hearing subjects and patients with sensorineural hearing loss. Scand Audiol (14)2 83.

Olsen, W.O., Pratt, T.L., Bauch C.D. (1997). Consistency in latency measurements and interpretation of ABR tracings.American Journal of Audiology, (6)57-62.

Prepare the equipment 

1. Turn on Titan by pressing the R or L button.
2. Choose the test protocol from the list using the up & down arrow keys and then press Select.
3. To use a different protocol than the one selected, press Protocol and then repeat step 2 above.
4. Select the transducer (only if more than one connected to the preamplifier).
5. Select the ear for testing.

Test environment 
The ideal test environment is a quiet room where lights and other electronic equipment are turned off.

Prepare the Infant 

Patient state	The infant should be sleeping or in quiet relaxed state. Sucking, blinking, crying or movement may affect testing.
Skin preparation	Typically, no skin preparation is required. If the infant’s skin is oily, the electrode placement sites should be cleaned using alcohol wipes and/or skin preparation gel. Use a conductive gel with the electrodes to improve impedances.
Place electrodes	Place surface electrodes using the desired montage (mastoid or nape).
Connect cables	Connect the cables from the PreAmplifier to the respective surface electrodes.

Check impedance
Impedances are indicated by the green/amber dots on the infant as well as in numerical format on screen.

When the dot is amber, this means the impedance is poor (> 40kΩ). In this instance, it may be necessary to clean the skin and replace the surface electrode.

NB. Testing is possible when impedances are poor. This may, however, affect test time and measurements.

Place transducer/s
Place the probe or insert earphones in the infant’s ear/s or place the headset over the infant’s ears.

The probe light will turn green when a good seal is obtained.

Run test
Press the START button on the Titan or press the preamplifier button.

Patient noise (EEG)
After starting the test, the patient noise/EEG bar is displayed at the top of the screen.

If the patient noise goes above the black line, try to calm the infant to reduce movement, crying, sucking etc.

If the infant appears calm and the patient noise is not ideal, stop the test and select a protocol with a higher rejection level (if available).

If the patient noise/EEG signal is still not ideal, refer to the EEG troubleshooting section below.

Results

PASS result

REFER result

PASS – when the result reaches 100% for the pass criteria, PASS is displayed in green above the measurement.
REFER – when the result does not reach 100% for the pass criteria within the measurement time, REFER is displayed in amber above the measurement.
INCOMPLETE – if the test is stopped before a PASS or REFER is generated by the system, INCOMPLETE is displayed above the measurement indicating that the full test was not completed.

EEG troubleshooting 
When the patient noise/EEG signal is poor and the patient is calm, try the following:

• Turn off (if possible) all electronic devices/sources, such as lights, computers, mobile phones etc.
• Ensure that the Titan battery is not being charged (via the cradle) during testing.
• If impedances were initially poor, clean the skin/use conductive gel and replace the electrodes.

Prepare the equipment

1. Turn on Titan by pressing the R or L button.
2. Open the OtoAccess or Noah database and enter new patient details.
3. Double click on the Titan Suite icon to launch the software and click on the ABRIS module tab.
4. Select the desired test protocol from the dropdown list.
5. Select the ear for testing.

Test environment 
The ideal test environment is a quiet room where lights and other electronic equipment are turned off.

Prepare the Infant 

Patient state	The infant should be sleeping or in quiet relaxed state. Sucking, blinking, crying or movement may affect testing.
Skin preparation	Typically, no skin preparation is required. If the infant’s skin is oily, the electrode placement sites should be cleaned using alcohol wipes and/or skin preparation gel. Use a conductive gel with the electrodes to improve impedances.
Place electrodes	Place surface electrodes using the desired montage (mastoid or nape).
Connect cables	Connect the cables from the PreAmplifier to the respective surface electrodes.

Check impedance
At the top of the screen, the impedance is indicated by the green/amber dots on the infant image.

When the dot is amber, this means the impedance is poor (> 40kΩ). In this instance , it may be necessary to clean the skin and/or use some conductive gel and replace the surface electrode.

NB. Testing is possible when impedances are poor. This may, however, affect test time and measurements

Place transducer/s
Place the probe or insert earphones in the infant’s ear/s or place the headset over the infant’s ears.

The probe light will turn green when a good seal is obtained.

Run test 
Click on START in the software, press the spacebar or press the preamplifier button.

Patient noise (EEG)
After starting the test, patient noise or EEG is displayed at the top of the screen (depending on setup).

The dark green bars should not reach the black bar

The EEG indicator should remain green

If the patient noise goes above the black line/EEG indicator turns red, try to calm the infant to reduce movement, crying, sucking etc.
If the infant appears calm and the patient noise/EEG is not ideal, stop the test and increase the rejection level using the arrow buttons.
If the patient noise/EEG signal is still not ideal, refer to the EEG troubleshooting section below.

Results

PASS result

REFER result

PASS –  when the result reaches 100% for the pass criteria, PASS is displayed in green above the measurement.
REFER –  when the result does not reach 100% for the pass criteria within the measurement time, REFER is displayed in amber above the measurement.
INCOMPLETE –  if the test is stopped before a PASS or REFER is generated by the system, INCOMPLETE is displayed above the measurement indicating that the full test was not completed.

EEG Troubleshooting 
When the patient noise/EEG signal is poor and the patient is calm, try the following:

• Turn off (if possible) all electronic devices/sources, such as lights, computers, mobile phones etc.
• Ensure that the Titan battery is not being charged (via the cradle) during testing.
• If impedances were initially poor, clean the skin/use conductive gel and replace the electrodes.

1. Prepare the infant’s skin before placing electrodes (if required). Clean oily skin using alcohol wipes/skin preparation gel. Use a small amount of conductive electrode gel to improve impedances.
   

   Forehead	Right mastoid	Left mastoid

2. Place the surface electrodes (on the prepared skin).
   

   Forehead	Right mastoid	Left mastoid

3. Attach the electrode cables to the surface electrodes.
   
   
   NB: Ensure the electrode cables are correctly attached to the preamplifier.
   

There are a number of things to consider when conducting OAE testing in order to ensure valid and reliable results. Consideration of the factors below will ensure an optimal OAE test.

1. Probe and cable configurations
   Ensure that the protocol that you select or create is valid for the test population and for the expected clinical outcome. Protocols generally differ between those used for Newborn Hearing Screening where a clinical outcome is based on a single test versus those used in a diagnostic follow up situation where the OAE result forms part of an overall test battery approach where many tests are analyzed to form a conclusion.

   Refer to the Titan Additional Information manual for more details about test parameter considerations when creating an OAE protocol. This document also highlights parameters to consider when creating a screening
   TEOAE protocol: Neonatal Hearing Screening and Assessment (2002). Transient Evoked Oto-Acoustic Emission (TEOAE) Testing in Babies. 

   
   
2. Probe and cable configurations
   When performing OAE testing with Titan, it is important to use either the Long Clinical Extension cable with the shoulder box or the Preamplifier cable. As described in the manual, testing must not be conducted while the probe is directly connected to the Titan or directly connected to the Preamplifier cable. OAE tests should not be performed while holding the probe in the patient’s ear as this increases noise levels and the chance of incorrect delivery of the stimulus.
   
   
   
3. Daily Probe Test
   Probe performance is crucial to OAE test results. It is common practice to conduct a probe test at the beginning of each day before starting to test on patients to ensure that the probe is functioning correctly.
   • Before conducting the probe test, ensure that the probe tip is clean and free of wax and/or debris.
   • Always conduct the probe test in a quiet test environment.
   • Only use the recommend cavity for testing. Using a different type of cavity may not detect probe faults.

   Refer to the TEOAE Probe Test Quick Guide for more information.

4. Cleaning the probe tip
   It is important that the probe tip is clean and free of wax or other debris before conducting a test. Wax or debris in the probe tip can cause incorrect presentation of the stimulus or recording of the OAE. Refer to the manual or the Cleaning the Titan Probe Tip Quick Guide for more information.
   
   
   
5. Probe placement
   A good probe placement will ensure a good test. Ensure that the correct size ear tip is selected so that the probe does not fall out of the ear during testing. Refer to the Selecting the Correct Ear Tip for Titan Quick Guide for more information.
   
   
   
6. Test environment
   Ambient and physiological (patient) noise can affect the recording of an OAE response significantly. It is very important to conduct testing in a quiet environment and instruct the patient to be still and quiet during the entire test.
   
   
   
7. Analyzing the result
   Depending on the type of test, screening vs diagnostic, the test analysis will differ. In screening, the protocol usually provides pass/refer labels for ease of understanding. In diagnostics, the stimulus, probe check, response waveform and OAE response graph along with SNR values are usually analyzed to form a conclusion of the test result.

Prepare the equipment 

1. Turn on Titan by pressing the R or L button.
2. Open the OtoAccess or Noah database and enter new patient details.
3. Double click on the Titan Suite icon to launch the software and click on the DPOAE module tab.
4. Select the desired test protocol from the dropdown list.
5. Select the ear for testing.

Test environment
The ideal test environment is a quiet room. High ambient background noise adversely affects OAE measurements.

Prepare the baby
The baby should be sleeping or in quiet relaxed state. Sucking, blinking, crying or movement may affect testing.

Place transducer
Place the probe in the ear –  the light will turn green when a good seal is obtained.

Run test
Click on START in the software, press the spacebar or press the shoulder box button.

Results

PASS result

REFER result

PASS –  when the criteria for a pass are reached, PASS is displayed in green above the measurement.
REFER –  when the criteria for a pass are not reached within the measurement time, REFER is displayed in amber above the measurement.
INCOMPLETE –  if the test is stopped before a PASS or REFER is generated by the system, INCOMPLETE is displayed above the measurement indicating that the full test was not completed.

1. Turn on Titan by pressing the R or L button.

2. Select a tympanometry protocol (e.g., Tymp 226Hz) and record tympanometry measurements on the left and right ear.

3. Save the tympanometry measurements to the handheld unit. Note: Tympanometry results do not need to be saved in order for the handheld unit to use the last recorded MEP data for pressurized OAE testing.

4. Select a pressurized DPOAE protocol.

5. Ensure the correct test ear is selected, so that the correct MEP is used from the tympanometry test.

6. Press the start button and record the OAE. Change ears and repeat.

7. Save results on the handheld unit.

Select a tymp protocol	Record tympanograms	Select a Pressurized DPOAE protocol	Record & save DPOAE results

 

Note: Ensure that the Titan handheld unit is turned off between patients. The Titan handheld unit will always use the last recorded MEP measurements (right and left ear) for the pressurized OAE test.

Prepare the equipment

1. Turn on Titan by pressing the R or L button.
2. Choose the test protocol from the list using the up & down arrow keys and then press Select .
3. To use a different protocol than the one selected, press Protocol  and then repeat step 2 above.
4. Select the ear for testing.

Test environment
The ideal test environment is a quiet room. High ambient background noise adversely affects OAE measurements.

Prepare the baby
The baby should be sleeping or in quiet relaxed state. Sucking, blinking, crying or movement may affect testing.

Place transducer
Place the probe in the ear –  the light will turn green when a good seal is obtained.

Run test
Press the START button on the Titan or press the shoulder box button.

Results

PASS result

REFER result

PASS –  when the criteria for a pass are reached, PASS is displayed in green above the measurement.
REFER –  when the criteria for a pass are not reached within the measurement time, REFER is displayed in amber above the measurement.
INCOMPLETE –  if the test is stopped before a PASS or REFER is generated by the system, INCOMPLETE is displayed above the measurement indicating that the full test was not completed.

1. Turn on Titan by pressing the R or L button.

2. Select a tympanometry protocol (e.g., Tymp 226Hz) and record tympanometry measurements on the left and right ear.

3. Save the tympanometry measurements to the handheld unit. Note: Tympanometry results do not need to be saved in order for the handheld unit to use the last recorded MEP data for pressurized OAE testing.

4. Select a pressurized TEOAE protocol.

5. Ensure the correct test ear is selected so that the correct MEP is used from the tympanometry test.

6. Press the start button and record the OAE. Change ears and repeat.

7. Save results on the handheld unit. 

Select a tymp protocol	Record tympanograms	Select a Pressurized TEOAE protocol	Record & save TEOAE results

Note: Ensure that the Titan handheld unit is turned off between patients. The Titan handheld unit will always use the last recorded MEP measurements (right and left ear) for the pressurized OAE test.

Prepare the equipment 

1. Turn on Titan by pressing the R or L button.
2. Choose the test protocol from the list using the up & down arrow keys and then press Select .
3. To use a different protocol than the one selected, press Protocol  and then repeat step 2 above.
4. Select the ear for testing

Test environment 
The ideal test environment is a quiet room. High ambient background noise adversely affects OAE measurements.

Prepare the baby
The baby should be sleeping or in quiet relaxed state. Sucking, blinking, crying or movement may affect testing.

Place transducer
Place the probe in the ear –  the light will turn green when a good seal is obtained.

Run test
Press the START button on the Titan or press the shoulder box button.

Results

PASS result

REFER result

PASS –  when the criteria for a pass are reached, PASS is displayed in green above the measurement.
REFER –  when the criteria for a pass are not reached within the measurement time, REFER is displayed in amber above the measurement.
INCOMPLETE –  if the test is stopped before a PASS or REFER is generated by the system, INCOMPLETE is displayed above the measurement indicating that the full test was not completed.

Prepare the equipment 

1. Turn on Titan by pressing the R or L button.
2. Open the OtoAccess or Noah database and enter new patient details.
3. Double click on the Titan Suite icon to launch the software and click on the TEOAE module tab.
4. Select the desired test protocol from the dropdown list.
5. Select the ear for testing.

Test environment
The ideal test environment is a quiet room. High ambient background noise adversely affects OAE measurements.

Prepare the baby
The baby should be sleeping or in quiet relaxed state. Sucking, blinking, crying or movement may affect testing.

Place transducer 
Place the probe in the ear –  the light will turn green when a good seal is obtained.

Run test
Click on START in the software, press the spacebar or press the shoulder box button.

Results

PASS result

REFER result

PASS –  when the criteria for a pass are reached, PASS is displayed in green above the measurement.
REFER –  when the criteria for a pass are not reached within the measurement time, REFER is displayed in amber above the measurement.
INCOMPLETE –  if the test is stopped before a PASS or REFER is generated by the system, INCOMPLETE is displayed above the measurement indicating that the full test was not completed.

Table of contents

1. What is the acoustic reflex?
2. Why perform acoustic reflex measurements?
3. How to set up the reflex protocol
4. How to perform acoustic reflex testing
5. Reasons for repeating reflex measurements
6. Probe and contra headphone placement
7. Normal acoustic reflexes
8. Non-reflexes
9. Acoustic reflex patterns
10. Acoustic reflex decay
11. References

What is the acoustic reflex?

The acoustic reflex is the contraction of the stapedius muscle elicited by the presentation of an acoustically loud sound.

When either ear is presented with a loud sound, the stapedius muscles on both sides contract.

Contraction of the stapedius muscle tilts the anterior stapes away from the oval window and stiffens the ossicular chain.

This results in increased impedance which is measured as a small decrease in compliance by an ear canal probe.

The stapedius muscle is innervated by the seventh cranial (facial) nerve (CNVII).

So, in the presence of CNVII paralysis, the stapedius muscle is likely to be affected.

Why perform acoustic reflex measurements?

Acoustic reflex results make a major contribution to differential diagnosis and should be part of every basic audiological evaluation.

They can provide/confirm information about the type (conductive, sensory, neural) and degree of hearing loss.

An acoustic reflex will most likely be elicited if all the following conditions are met:

• Normal middle ear function
• Loud enough stimulus to elicit the response
• No abnormal adaptation to stimulus

Yet, about 5% of the adult population have absent acoustic reflexes.

The pure tone intensity range to elicit an acoustic reflex is 70 to 100 dB HL (median = 85 dBHL).

Ipsilateral acoustic reflex thresholds (ARTs) in patients with normal hearing are usually 70-80 dB above their pure tone thresholds, and about 5 dB greater for their contralateral threshold.

So, if pure tone thresholds were at 10 dB HL, you would expect ipsilateral ARTs between 80-90 dB HL and contralateral ARTs between 85-95 dB HL.

Contraindications for acoustic reflex testing are:

• Tinnitus
• Outer ear infection
• Severe recruitment
• Hyperacusis

How to set up the reflex protocol

There are several parameters you need to take into consideration when setting up the reflex protocol.

 

1. Ipsi- and contralateral pathways

You can either measure the ipsilateral pathway, contralateral pathway, or both.

Ipsilateral means ‘same side’ and contralateral means ‘opposite side’.

The reflexes are always indicated by the probe ear.

For both pathways, the loud sound travels through the outer, middle, and inner ear, then along the vestibulocochlear nerve (CNVIII) to the brainstem arriving at the cochlear nucleus.

From here the signal travels to the superior olivary complex and to the CNVII nuclei.

The signal is then sent down the CNVII causing contraction of the stapedius muscle.

 

2. Probe tone

Use a 226 Hz probe tone unless you are testing neonates.

In this case, use a high-frequency probe tone (1000 Hz).

 

3. Continuous or pulsed stimulus

The pulsed stimulus provides the opportunity to measure ipsilateral reflexes using a 1000 Hz tone.

Also, the pulsed stimulus lowers the risk of false reflexes that may occur at high intensities in cavities.

Yet, using the pulsed stimulus doubles the test time relative to the continuous stimulus.

Thus, the continuous stimulus is better in scenarios where you measure using a 226 Hz probe tone, at normal intensities, and when measuring contralateral reflexes.

The pulsed stimulus is better at high intensities, where there is a risk of false passes in cavities, and when measuring ipsilateral reflexes on infants using a 1000 Hz probe tone.

There is little difference in the morphology of the reflex when using a pulsed relative to continuous stimulus, so it is something to keep in mind in the interpretation of the test results (Figure 1).

Figure 1: Pulsed vs continuous reflex morphology.

 

4. Acoustic reflex threshold (ART)

The ART is the lowest intensity of an acoustic stimulus that elicits a measurable change in acoustic immittance.

A change or threshold criteria of 0.03 is usually taken as the smallest change required to confirm the presence of a reflex (Figure 2).

Figure 2: Threshold criteria.

 

5. Test frequencies

ART measurements are usually conducted at 500, 1000, 2000, and 4000 Hz.

Results are variable at 4000 Hz and many normal-hearing adults have elevated ARTs at this frequency.

Thus, you should view results with caution.

Some clinicians prefer to use a broadband noise as an alternative to 4000 Hz.

Generally, noise stimuli elicit reflexes at lower levels than pure tones do; approximately 20 dB lower.

 

6. Intensity

The intensity should start from 70-80 dB HL up to 105 dB HL in 5 dB steps until an acoustic reflex threshold is obtained.

Depending on the required outcome of testing (screening vs clinical), it is not recommended to go above 105 dB HL unless you suspect a conductive loss.

Going above this level can cause permanent hearing damage and tinnitus.

 

7. Positive or negative reflex display

Reflexes are either displayed positively or negatively, depending on your setup (Figures 3 and 4).

Figure 3: A negatively displayed reflex.

Figure 4: A positively displayed reflex.

How to perform acoustic reflex testing

The procedure is outlined below step-by-step.

 

Step 1

Alert the client that they will hear some loud sounds in either ear.

Ask them to sit still and quiet.

 

Step 2

Place the immittance probe (probe used for tympanometry) into the ear you want to test.

Place the contralateral probe into the other ear.

 

Step 3

Perform tympanometry first.

You should measure acoustic reflexes with the ear canal pressure set to the largest compliance in the presence of the 226 Hz probe tone.

 

Step 4

Press Start.

The measure will then run a reflex growth and stop when a reflex is present with the defined threshold criteria.

If the tone is loud enough and a contraction of the stapedius muscle occurs, the immittance probe will record that an acoustic reflex is present.

 

Step 5

The presence of a reflex is automatically confirmed by running the measure twice at the same intensity to confirm that the found threshold is reproducible.

Or you can repeat the measure manually 5 dB above the ART obtained to ensure it is a true ART.

Reasons for repeating reflex measurements

If any of the following occur during testing, it is wise to re-test to confirm your results are true:

(1) Patient swallows, talks, laughs, coughs or similar during the test.

(2) You get an odd result that does not look correct or does not match audiogram findings. When in doubt, repeat the test to check your results are repeatable.

(3) Collapsed canals can lead to false results, particularly if a headphone is used on the contralateral ear. Re-check results if they look suspicious or do not fit with other results in the test battery.

Probe and contra headphone placement

The reflexes are indicated by the probe ear.

So, when obtaining the reflexes for the right ear, place the probe in the patient’s right ear and the contra headphone on the left ear (Figure 5).

Figure 5: Probe and contra headphone placement for right ear acoustic reflexes.

When obtaining reflexes for the left ear, place the probe in the left ear and the contra headphone on the right ear (Figure 6).

Figure 6: Probe and contra headphone placement for left ear acoustic reflexes.

Normal acoustic reflexes

Your results should show:

• The presence or absence of the stapedial reflex
• An acoustic reflex threshold
• Acoustic reflex decay or adaptation (if tested)

The following is an example of what a reflex should look like (Figure 7).

Figure 7: Normal acoustic reflex.

The deflection value (0,07) is shown when a reflex is present.

But detection is based on the measurement matching an algorithm.

Thus, it is important to look at the morphology of the reflex in conjunction with your testing situation and decide if the reflex is in fact a ‘true’ reflex and not an artifact.

A reflex should show a negative deflection from 0,00 ml, which is time-locked to the stimulus presentation.

It will then hold the change in compliance before offsetting back to 0,00 ml (Figure 8).

Figure 8: Negative deflection at onset.

You will note in the example above that the reflex goes into the negative part of the graph before moving to the positive deflection point of 0,05 ml.

This type of response is biphasic and can occur at the onset or both onset and offset of the reflex.

The abnormal pattern of a biphasic response at both onset and offset is associated with otosclerosis, particularly in its early stages.

Non-reflexes

Non-reflexes occur when:

• The reflex does not meet the deflection criteria
• Patient moves, swallows, or speaks during the test, which creates artifacts

In the former, it may appear to be a reflex, but the deflection value is not large enough to meet the given criteria (Figure 9).

Figure 9: Non-reflex due to deflection value that does not meet the criteria.

In Figure 10, the system has detected this as a reflex (highlighted in green), but it is in fact an artifact.

Figure 10: Non-reflex due to artifact.

You can tell by looking at the shape that it does not match the pattern of a normal acoustic reflex.

In this instance, you should repeat the test at that frequency to confirm the true ART.

Acoustic reflex patterns

Below are various reflex patterns you may come across during testing.

These are not the results or patterns that you will see every time you test and real‑life clinical interpretations are much more complex.

Different authors publish patterns or record results in different ways.

Thus, the tables below are estimative.

Note that reflexes at 4000 Hz may or may not be present due to variability at this frequency.

You may wish to use broadband noise as an alternative to testing at 4000 Hz.

 

1. Normal hearing and middle ear function

In patients with normal hearing and middle ear function, both ipsilateral and contralateral reflexes will be present at all frequencies (Table 1).

	Frequency	.5 kHz	1 kHz	2 kHz	4 kHz
Probe R	Stim R (ipsi)	85	85	85	85
	Stim L (contra)	90	90	90	90
Probe L	Stim L (ipsi)	80	80	80	80
	Stim R (contra)	85	85	85	85

Table 1: Normal hearing and middle ear function.

 

2. Conductive hearing loss

Acoustic reflexes will be absent when a probe is placed in an ear with a middle ear disorder.

This is because middle ear disorders typically prevent the probe from measuring a change in compliance when the stapedius muscle contracts.

Reflexes will therefore be absent even in the case of a mild conductive hearing loss (Table 2).

In the presence of a Type C tympanogram, depending on the degree of negative pressure in the middle ear, reflexes can be either present or absent.

Conductive hearing loss is unlikely if acoustic reflexes are present in the probe ear, except in the rare case of superior semicircular canal dehiscence (SSCD).

	Frequency	.5 kHz	1 kHz	2 kHz	4 kHz
Probe R	Stim R (ipsi)	85	85	85	85
	Stim L (contra)	100	100	100	105
Probe L	Stim L (ipsi)	X	X	X	X
	Stim R (contra)	X	X	X	X

Table 2: Normal hearing in the right ear and a mild conductive loss in the left ear.

In Table 2, the raised left contralateral reflex thresholds (probe right, stimulus left) are due to the extra sound pressure level (SPL) needed to overcome the mild loss in the left ear.

The mild middle ear pathology may affect signals traveling through the left ear or being measured in the left ear.

They will either be absent or raised.

	Frequency	.5 kHz	1 kHz	2 kHz	4 kHz
Probe R	Stim R (ipsi)	85	85	85	85
	Stim L (contra)	X	X	X	X
Probe L	Stim L (ipsi)	X	X	X	X
	Stim R (contra)	X	X	X	X

Table 3: Normal hearing in the right ear and a moderate conductive loss in the left ear.

In Table 3, the stimulus was not loud enough to elicit the stapedius reflex in the left contralateral recording (probe right, stimulus left), as we are dealing with a moderate conductive loss.

 

3. Cochlear hearing loss

In ears with a cochlear hearing loss, it is possible for the acoustic reflex to be elicited at sensation levels of less than 60 dB.

The sensation level is the difference between the ART and the hearing threshold.

For example, if the hearing threshold at 1 kHz is 50 dB HL and the ART is 90 dB HL, the sensation level is 40 dB.

A sensation level of less than 60 dB is a positive Metz test.

This indicates a cochlear site of lesion (sensorineural loss) due to the loudness recruitment phenomenon.

	Frequency	.5 kHz	1 kHz	2 kHz	4 kHz
Probe R	Stim R (ipsi)	85	80	80	100
	Stim L (contra)	85	90	90	X
Probe L	Stim L (ipsi)	85	90	85	100
	Stim R (contra)	90	80	85	X

Table 4: A mild to moderate cochlear loss in both ears.

In Table 4, note that the ARTs occur at about normal levels.

This is because the ART in an ear with a cochlear loss may resemble the results of a normal ear when the air conduction thresholds are below 50 dB HL.

As the hearing threshold increases above this level, the chance of recording a raised or absent acoustic reflex increases.

	Frequency	.5 kHz	1 kHz	2 kHz	4 kHz
Probe R	Stim R (ipsi)	85	85	85	95
	Stim L (contra)	X	X	X	X
Probe L	Stim L (ipsi)	X	X	X	X
	Stim R (contra)	90	90	90	95

Table 5: Severe to profound cochlear loss in the left ear; normal hearing in the right ear.

In Table 5, the stimulus was not loud enough to elicit a stapedius reflex due to the severe to profound loss in the left ear.

Thus, whenever a stimulus is presented to the affected ear, reflexes will be absent/raised in both ipsilateral and contralateral recordings as shown above.

 

4. Retrocochlear hearing loss

ARTs in ears with a retrocochlear (CNVII) pathology are usually elevated above what they would have been for normal hearing or a cochlear hearing loss.

Often, they are absent at the greatest stimulus levels.

Keep in mind that you should analyze ART results in combination with the patient’s case history, audiogram, speech audiometry findings, and tympanometry findings for differential diagnosis.

Some things to note:

• Ears with a retrocochlear pathology and normal hearing do not have reflexes 30% of the time
• With a mild 30 dB hearing loss, the likelihood of absent reflexes increases
• The absence of reflexes at 0.5, 1, and 2 kHz in normal hearing patients must be considered suspicious unless proven otherwise
• The affected ear will show absent acoustic reflexes when a stimulus is presented to it in the case of a CNVIII lesion

	Frequency	.5 kHz	1 kHz	2 kHz	4 kHz
Probe R	Stim R (ipsi)	80	80	80	90
	Stim L (contra)	105	110	X	X
Probe L	Stim L (ipsi)	110	X	X	X
	Stim R (contra)	85	80	85	95

Table 6: Retrocochlear lesion in the left ear; normal hearing in both ears.

In Table 6, note the raised/absent acoustic reflexes with presentation to the left ear.

	Frequency	.5 kHz	1 kHz	2 kHz	4 kHz
Probe R	Stim R (ipsi)	80	80	85	85
	Stim L (contra)	X	X	X	X
Probe L	Stim L (ipsi)	X	X	X	X
	Stim R (contra)	85	85	90	90

Table 7: Retrocochlear lesion in the left ear; mild hearing loss in the left ear; normal hearing in the right ear.

In Table 7, note the absent acoustic reflexes when sound is presented to the left ear.

 

5. Facial nerve/CNVII involvement

Acoustic reflexes are absent when measured on the affected side in the case of a facial nerve disorder.

This is because the stapedius muscle is innervated by the CNVII.

Often, CNVII disorders are recognizable, such as facial paralysis in the case of Bell’s palsy.

Measuring the acoustic reflex is used as a tool to track the recovery process in such patients.

	Frequency	.5 kHz	1 kHz	2 kHz	4 kHz
Probe R	Stim R (ipsi)	80	80	85	85
	Stim L (contra)	85	85	85	90
Probe L	Stim L (ipsi)	X	X	X	X
	Stim R (contra)	X	X	X	X

Table 8: Facial nerve/CNVII lesion in the left ear due to Bell’s palsy; normal hearing in both ears.

In Table 8, note that the acoustic reflexes are absent when the probe is inserted into the left ear.

Also, you will recognize this is a similar pattern of results for a CNVIII lesion.

 

6. Intra-axial brainstem lesion

This is a very rare condition; about 1 in 10 million.

Acoustic reflexes are normal ipsilaterally and absent contralaterally (Table 9).

The left and right pathways are disrupted by a lesion involving the auditory fibers.

	Frequency	.5 kHz	1 kHz	2 kHz	4 kHz
Probe R	Stim R (ipsi)	80	80	85	85
	Stim L (contra)	X	X	X	X
Probe L	Stim L (ipsi)	85	80	80	85
	Stim R (contra)	X	X	X	X

Table 9: Intra-axial brainstem lesion; normal hearing in both ears.

Acoustic reflex decay

Acoustic reflex decay testing can be useful in detecting/confirming a retrocochlear pathology.

Generally, patients will present with typical retrocochlear indicators, such as unilateral tinnitus, asymmetrical hearing loss, and vertigo.

You will often have enough information to warrant a referral to an ENT specialist without needing to do this test.

But the test may be useful when the audiogram and case history are normal, but reflex results show a retrocochlear pattern.

So, let’s dive in.

 

What is the acoustic reflex decay test?

The acoustic reflex decay test measures whether a reflex contraction is maintained or weakens during continuous stimulation (usually 10 seconds).

The test is usually conducted at 500 Hz and 1000 Hz, but not above these frequencies as even normal ears can show decay at higher frequencies.

The test is performed by presenting a continuous stimulus 10 dB above the ART for the given frequency for a period of 10 seconds.

The size of the reflex response will either stay the same or decrease during the 10-second period.

What you are looking for is whether the response decays to half its original size.

So, if the reflex response decreases to 50% of its original size within the 10 seconds of testing, the test would be positive for reflex decay.

Figure 11: Examples of acoustic reflex decay tests. Source: Gefland, 2001.

In Figure 11 (Gefland, 2001), the acoustic reflex decay is considered negative if the reflex response does not decrease (a) or if it decreases by less than half of its original size (b).

Reflex decay is positive if the magnitude falls by 50% or more (c).

 

How to perform the acoustic reflex decay test

The procedure is outlined below step-by-step.

 

Step 1

Perform tympanometry and reflex measurements first.

 

Step 2

Take the acoustic reflex threshold at 500 Hz or 1000 Hz in the ear you want to test and add 10 dB.

This is the stimulus level you will use for testing.

 

Step 3

Make sure you have a good probe seal and press start to run the test.

 

Caveat

If the reflex decay test is positive, you should check that it was not due to an improper seal, which might produce an artifact like a decaying curve.

 

Interpretation of reflex decay

The decay value is the percentage difference between the two reflex deflection values taken half a second after the stimulus started and half a second before the stimulus stopped.

The test is either negative (Figure 12) or positive (Figure 13).

 

Figure 12: Negative reflex decay test, as the response did not decay by more than 50% (green dotted line).

Figure 13: Positive reflex decay test, as the response decayed by more than 50% (green dotted line).

References

Bess, F.H., & Humes, L.E. (2003). Audiology: The Fundamentals (3rd ed.). Baltimore: Lippincott Williams & Wilkins.

Campbell, K.C., & Mullin, G. (2018). Impedance Audiometry. Retrieved March 29, 2021, from https://emedicine.medscape.com/article/1831254-overview.

Emmanuel, C. D. (2009). Acoustic Reflex Threshold (ART) Patterns: An Interpretation Guide for Students and Supervisors. Retrieved March 29, 2021, from https://www.audiologyonline.com/articles/acoustic-reflex-threshold-art-patterns-875.

Fowler, C. G., & Shanks, J. E. (2002). Tympanometry. In J. Katz (Ed.), Handbook of Clinical Audiology (5th ed.). (pp. 175-204). Baltimore: Lippincott Williams & Wilkins.

Gefland, S.A. (2001). Essentials of Audiology (2nd ed.). New York: Thieme Medical Publishers, Inc.

Margolis, R. H., & Hunter, L. L. (2000). Acoustic Immittance Measurements. In R. J. Roeser, M. Valente & H. Hosford- Dunn (Ed.), Audiology Diagnosis. (pp. 381 - 423). New York: Thieme Medical Publishers, Inc.

Srireddy, S. V., Ryan, C. E., & Niparko, J. K. (2003). Evaluation of the patient with hearing loss. In J. Niparko & L. R. Lustig (Ed), Clinical neurotology: Diagnosing and managing disorders of hearing, balance and the facial nerve. (pp. 65-80). London: Martin Dunitz Publishing.

Zito F, Roberto M. The acoustic reflex pattern studied by the averaging technique. Audiology. 1980;19(5):395-403. doi: 10.3109/00206098009070073. PMID: 7436858. 

 

Description
Electrical Evoked Stapedial Reflex Thresholds (eSRT) can be a very useful objective measure for the upper stimulus levels during the programming of a cochlear implant (Brickley et al., 2005; Buckler et al., 2003). The measure is particular useful during the fitting of cochlear implants in pediatrics (Cowdrey & Dawson, 2003), but also during the fitting on adults in particular adults unable to provide reliable behavioral measures (Andrade KC et al., 2013, Wolfe & Kasulis, 2008).

Required Items

• A PC controlled Titan with an eSRT license.

When using the Titan to obtain the eSRT levels, the cochlear implant is used as the stimulus source, while the Titan is used for monitoring. Titan monitors if there is any change as a function of time when a stimulus is presented through the cochlear implant.

eSRT protocol setup
Enter Menu –  Seup –  Protocol Setup and create a protocol pressing New. Add the eSRT test as a protocol by selecting and pressing Add . Press Settings  to modify the protocol created.

eSRT parameters

	Set the probe tone frequency to 226 Hz, 678 Hz, 800 Hz, 1000 Hz.
	Check the box to obtain an eSRT at the ambient pressure. If unchecked, the pressure will be obtained at peak pressure, if a peak pressure is present.
	The more smoothing that is applied, the less noisy/detailed the trace will be. The smoothing level can be set from 0-4, with 0 being no smoothing applied and 4 being maximum smoothing applied.

Display

	Set the display of the reflexes to positive to have a positive deflection and negative to have a negative deflection of the reflexes.
	This setting adds a threshold line to the graph, so it is possible to see when a threshold is present, e.g. by setting it for 0.05 ml.

Once the protocol is modified, press OK to save the changes to the protocol.

eSRT Test Screen

1	Protocol	Select an eSRT protocol.
2	Probe tone	226Hz, 678 Hz, 800 Hz, 1000 Hz.
3	Probe status	Indicates probe status (in ear, out of ear, leaking, blocked).
4	Target pressure	Indicates how far the pressure is from target pressure.
5	Tests in protocol	Lists the tests that is part of the protocol, a checkmark at the right indicates the test is included, a checkmark at the left indicates data is obtained for the test.
6	Start/Stop	Start and stop the measurement. In case of drifting, Stop and Start the measure to reset the baseline.
7	Time scale	The time scale is continuous. Use the slider to move back and forth on the time scale.
8	Time scale	Press the end of the time scale to go back to the point in time of the running measurement.
9	Threshold indication	The dashed line indicates the setting of the reflex threshold level, which is used to see when a reflex is present.
10	Marker	Use the marker (M) to indicate when a reflex is present. This is done by clicking with the mouse in top of the reflex. As default the marker will indicate Mnumber  (time).
11	Marker	Edit the name of the marker to help you identify which electrode it is from. Press the trash bin to delete a marker. By pressing the marker in the table the view of the graph with go to the point in time of the marker to see the reflex.
12	Save and review session	Press Save or Save & Exit to save the session. Review a saved session from the session list.

eSRT Procedure

1. Open the Titan Suite so it runs in parallel with your cochlear implant fitting software.
2. It is recommended that tympanometry is performed prior to measuring the eSRT to ensure that the condition of the outer and middle ear is normal. Normal tympanograms are often a requirement for being able to measure reflexes in the first place.
3. Select the eSRT protocol you have created in the list of tests.
4. Instruct the patient that they do not have to say or do anything during the test, they just have to sit still. However, they should let you know if they at any time feel uncomfortable with the stimulus being presented through the cochlear implant.
5. Place the probe in the ear and ensure you get a tight seal. A good seal is important to avoid that the probe falls out of the ear during the measure.
   It is recommended to place the probe in the ear contralateral to the implant (Wolfe & Schafer, 2015).
   If there are any contraindications that the contralateral ear cannot be used for obtaining the eSRT, the reflex can be obtained ipsilaterally.
6. Press Start .
7. The Titan will monitor the changes as a function of time.
   Present the stimulus through the cochlear implant, one electrode at a time, and observe if a change occurs. It is recommended to present the stimulus in an ascending manner and increase the stimulus from the cochlear implant is sufficiently intense to elicit a deflection (Kosaner et al., 2009).
   Use the threshold indication line to see if a reflex is present.
   When a reflex is present, it can be marked pressing the area of the reflex with the mouse, this will assign a marker to the given reflex.
8. In case of drifting, Stop and Start the measure to reset the baseline. Please also ensure that the probe is placed properly in the ear. This can be monitored during the measurement using the Probe status and Target pressure .
9. Follow the procedure of 8-9 until you have obtained the eSRT for as many channels as possible. Remaining channels can be set using interpolation.
10. Press Save to save the measure. Note the markers cannot be edited once the measure has been saved.

---

References
Brickley, G., Boyd, P., Wyllie, F., O’Driscoll, M., Webster, D., & Nopp, P. (2005). Investigations into electrically evoked stapedius reflex measures and subjective loudness percepts in the MED-EL COMBI 40+ cochlear implant. Cochlear Implants International, 6(1), 31-42.

Buckler L., Dawson K, Overstreet E. (2003) Relationship between Electrical Stapedial Reflex Thresholds and HiRes Program Settings.

Wolfe J., Schafer EC. (2015) Programming Cochlear Implants, Plural Publishing Inc. 2nd Edition

Wolfe J., Kasulis H. (2008) Relationships among objective measures and speech perception in adult users of the HiResolution Bionic Ear. Cochlear Implants Int. 9(2), 70-81.

Andrade KC., Leal MC., Muniz LF., Menezes PL., Albuquerque KM., Carnaúba AT. (2013). The importance of electrically evoked stapedial reflex in cochlear implant. Braz J Otorhinolaryngol. 80(1):68-77.

Julie Kosaner, Ilona Anderson, Zerrin Turan, Martina Deible (2009), Use of ESRT in Fitting Children with Cochlear Implants, Int. Adv. Otol. 2009; 5:(1) 70-79.

Table of contents

1. What is speech audiometry?
2. Background
3. Speech detection threshold (SDT)
4. Speech recognition threshold (SRT)
5. Word recognition (WR)
6. Required equipment
7. Speech setup
8. Test procedure
9. Speech results
10. Speech in noise
11. Binaural speech
12. References

What is speech audiometry?

Basic speech audiometry uses speech signals to assess a person’s ability to hear speech, discriminate between words, and recall words. Advanced speech audiometry dives into the comprehension of speech.

Background

Many hearing aid users report trouble hearing speech, especially in noisy situations.

In this light, speech testing is a good tool to assess why the patient is troubled in certain hearing environments.

Speech audiometry employs speech signals and can be used to examine the processing ability and if it is affected by disorders of the middle ear, cochlea, auditory nerve, brainstem pathway, and auditory centers of the cortex.

More advanced speech testing considers how speech is understood in the presence of noise, such as:

• White noise
• Speech noise
• Babble noise

Using speech as the noise source can provide information on the signal-to-noise ratio (SNR) at which the patient can understand speech.

Other components such as the placement of the speech signal in relation to the noise source and the tonal differences between the speech signal and the masking signal are some of the things incorporated into advanced speech testing.

Speech detection threshold (SDT)

The speech detection threshold (SDT), also known as the speech reception threshold, is the level at which the patient can hear speech is present in 50% of the cases.

You can use the SDT as a cross-check of air conduction audiometry, which should closely agree with the pure‑tone average (PTA).

 

What is the pure-tone average (PTA)?

The PTA is the average of thresholds obtained at 500, 1000, and 2000 Hz.

For the PTA and SDT to ‘closely agree’, apply the following rules of thumb:

• ±6 dB or less = good
• ±7-12 dB = adequate
• ±13 dB or more = poor

Speech recognition threshold (SRT)

The speech recognition threshold (SRT) examines at which level the patient can repeat 50% of the speech material (usually numbers or spondaic words) correctly.

Also, the SRT gives an index of hearing sensitivity and helps to determine the starting point for other supra-threshold measures such as word recognition (WR).

Word recognition (WR)

WR, also known as speech discrimination (SD), is a score of the number of words correctly repeated, expressed as a percentage of correct (discrimination score) or incorrect (discrimination loss).

You can also score this as a phoneme score to know which phonemes the patient has difficulty hearing at a particular intensity level.

This is helpful for counseling and rehabilitation purposes.

 

Discrimination score / discrimination loss

You can either record this score in the Diagnostic Suite or with the audiometer keyboard on our standalone devices.

 

In the suite

Press the checkmark or the left arrow key to store a word as correctly repeated. Press the ‘X’ or the right arrow key to store a word as incorrectly repeated. Press the circle or ‘S’ on your keyboard to store the speech threshold in the speech graph (Figure 1).

Figure 1: Speech discrimination in the Diagnostic Suite.

 

On standalone devices

Press ‘Incorrect’ to store the word as incorrect or press ‘Correct’ to store the word as correct (Figure 2).

Figure 2: Speech discrimination with audiometer keyboard.

 

Phoneme score

When the speech material is indexed according to the number of phonemes in each word, the according soft key numbers will activate.

So, for a word with two phonemes, the soft keys ‘0’, ‘1’, and ‘2’ will be available to score.

When you score the word with the use of phonemes, the number of correct phonemes will appear below the word (Figure 3).

Figure 3: Words and their number of phonemes.

The phoneme score is calculated as a percentage: correct phonemes relative to total number of phonemes.

Required equipment

(1) Headphones, insert phones, or free field speakers

(2) A microphone, external sound player, or built-in wave files

(3) Talk back microphone and talk forward microphone

Speech setup

When running the speech test using wave files, you can present words in manual, continuous, or time out mode.

 

1. Manual mode

This allows you to manually press the tone switch/enter button to present the word and then score it as incorrect or correct before moving on to the next word.

 

2. Continuous mode

In this mode, the next word will automatically be presented after scoring incorrect or correct.

 

3. Time out mode

In this mode, the word played will be scored as either correct or incorrect if you do not enter the score within 1 to 5 seconds.

Test procedure

The procedure is outlined below step-by-step and is specific to our equipment.

 

Step 1

Before performing speech audiometry, you may wish to do the tone audiogram.

This provides valuable predictive information for speech testing, including information about when you need to apply masking.

 

Step 2

Press the ‘Tests’ button and select the ‘Speech’ test.

If needed, select the ‘Measurement type’ (WR1, WR2, WR3, SRT), ‘Type’ of measure (word, numbers, multi‑syllabic numbers, multi‑syllabic words), and ‘List’ of words using the soft buttons.

Select the intensity levels for channel 1. If you need to apply masking, configure channel 2 also.

 

Step 3

Explain to your patient that he/she will now hear some words/numbers/sentences though the earphones/free field speakers.

Instruct your patient to repeat what is said even though it may be very soft.

Encourage your patient to guess even if they are unsure about the word/number/sentence.

When performing the speech test in noise, instruct your patient to focus on the speech, not the noise.

 

Step 4

Press ‘Start’ to start presenting the words, numbers, or sentences.

Based on the settings for speech, you can score the response as ‘Correct’, ‘Incorrect’, or as the number of correct phonemes.

 

Step 5

Click on ‘Store’ to store the results.

Speech results

You can display the results in table mode or graph mode.

 

1. Table mode

Table mode allows for several SRTs using different test parameters, such as transducer type, test type, intensity, masking, and so forth (Figure 4).

Figure 4: Table mode.

 

2. Graph mode

When showing the SRT in graph mode, the speech audiogram calculates the SRT value, which is the distance in dB from the point where the normative curve crosses 50% to the point where the speech curve crosses 50% (Figure 5).