This Quick Guide is intended to give a brief explanation on how to fit CROS and BiCROS type hearing aids. The instructions in this guide have been adapted from the methods stated by Hayes (2006) and Pumford (2005), links to these articles are provided at the bottom of this document.
The following points of instruction apply to the whole of this document and will aid understanding as to what is being measured in the different conditions:
CROS Hearing Aids
The objective of this measurement is to make signals from the unaidable side of the head sound the same as signals from the side of the better or normal hearing ear.
Dedicated protocols have been created for optimum application of this test, please speak to your local distributor to get and import these for use.
Calibrate and insert the probe microphone into the better / normal hearing ear.
BiCROS Hearing Aids
The objective of this test is similar to what has been shown above, however there is a hearing aid on the better ear for which we need to take consideration for.
The same dedicated protocol as used in the CROS instructions above is used for optimum application of this test, please speak to your local distributor to get and import these for use.
Further Reading
For more information on this topic then please see the following articles:
Hayes, D. (2006). A Practical Guide to CROS/BiCROS Fittings.
Pumford, J. (2005). Benefits of probe-mic measures with CROS/BiCROS fittings.
Introduction
The Real Ear to Coupler Difference (RECD) is a measurement that accounts for the decibel difference across frequencies between SPL measured in the coupler and the SPL measure in the real ear, produced by the same transducer generating the same signal. This ensures that information about the patient’s occluded ear canal characteristics is obtained.
Due to the physically smaller size of the ear canals for infants and children compared to adults, and because it would be very difficult to do real-ear verification on them, the RECD is an important measurement in the pediatric hearing aid fitting process. It enables clinicians to verify the frequency/gain characteristics of the child’s hearing aid while it is attached to the 2cc BTE coupler, without the need to have the child’s ear physically present. Since children have physically smaller ears than adults, and smaller ears equals higher SPL, not taking the RECD into account would likely lead to over-amplification. For more information on RECD and the recommended guidelines for pediatric hearing aid fittings, please refer to the references at the end of this document.
Measuring the RECD
There are two ways of measuring the RECD: with the patient’s ear mould or with the SPL60 RECD probe tip.
Measuring with ear moulds will be a bit more precise than measuring with the SPL probe, however; in situations where a quick measurement is needed, using the SPL probe will be much quicker than measuring with the ear mould. In situations where no measurement can be obtained, it is recommended to use age appropriate, predicted RECD values. Instructions for all three methods are detailed below.
RECD measurement with earmold
Items required:
Figure 1: Measuring the RECD with an ear mould with Affinity 2.0 and Callisto™.
RECD Measurement with SPL60 Probe
Needed items:
Figure 2: Measuring the RECD using the SPL probe with Affinity 2.0 (a) and Callisto™ (b)
Using age appropriate predicted RECD values
If it is impossible to get an RECD measurement (ex: child is crying or uncooperative), it is recommended to use age appropriate predicted RECDs.
Own Mould versus SPL Probe
Whether the RECD is performed using the client’s own ear mould or the SPL probe may have an effect on the result. The benefit of using the client’s own ear mould is that the measurement will reflect your client’s actual residual volume whereas the SPL probe only provides an estimate. However, you may be in a situation where the ear mould is nonexistent, broken, or has an extremely bad fit. Furthermore, you might need to conduct measurements on children not willing to co-operate. In these situations the SPL probe offers the benefit of easy probe placement and measurement.
Below, see two RECD measured in the same ear using the SPL probe and own ear mould respectively. Note: the differences between the two ways of measuring. As can be seen above the curve measured with the client’s own ear mould is below 0 in the low frequencies. This may be due to ear mould effects such as the tightness of the fit and venting and in the insertion depth of the SPL probe or ear mould.
Using the RECD in the hearing aid fitting
The RECD can now be used for the hearing aid fitting. The RECD can be imported, if that feature is supported, manually into the hearing aid software. The fitting will be recalculated while taking the RECD into account3. To view the RECD values, click on Table View.
To proceed with the hearing aid verification, click on the REAR button; the software will automatically go into the coupler mode and it will then be possible to proceed with the verification. The default fitting formula will be DSL v5 Pediatrics. Use the hearing aid software to fine tune the hearing aid and to ensure that the output is matching the DSL targets for soft, average, and loud, using a speech stimuli (like the ISTS). Measure the MPO to ensure that the output for loud sounds is not hitting the UCL.
Visible Speech Mapping can also be used for coupler based fittings. This can be done by choosing the Visible Speech Mapping in the REM module, rather than the REM440 module it self. Note that Visible Speech Mapping requires a separate license.
For more information, please consult the Affinity 2.0 Additional Info and Callisto™ Additional Info documents, available on our website www.interacoustics.com.
1Not all hearing aid manufacturers support RECD imports. Contact the hearing aid manufacturers if unsure.
2If always using the SPL probe rather than ear moulds, it is possible to create a protocol to ensure that the “Use the insitu SPL probe” option is always ticked off. For information on how to create protocols, please refer to the Instructions for Use or Additional Info manuals for Affinity 2.0 or Callisto™.
3Not all hearing aid manufacturers’ software support the import of RECDs. If unsure, check with the hearing aid manufacturer.
References
Bagatto MP. Optimizing your RECD measurements.The Hearing Journal 2001; 54: 32, 34-36.
Bagatto MP. The Essentials of Fitting Hearing Aids to Babies. Seminars in Hearing 2013; 34:1, 19-26
Bagatto MP (2007). Learning the Art to Apply the Science: Common Questions Related to Pediatric Hearing Instrument Fitting.
McCreery, Ryan. RECD is a Reasonable Alternative to Real-Ear Verification. The Hearing Journal 2013; 66:7, 13-14. Munro, Kevin. Integrating the RECD into the Hearing Instrument Fitting Process.
Purdy, J and Sheila, T. (2008). Measuring RECD on a Young Child.
The purpose of this Quick Guide is to give clinicians a short introduction to Visible Speech Mapping during the hearing aid fitting process and patient counseling.
Introduction
Verification of the hearing aid fitting is a very important part of the fitting process. To try to make this process a bit easier, rather than using traditional real-ear measurements, hearing care professionals can use the Visible Speech Mapping modules in the Affinity 2.0 and Callisto™ suites. Visible Speech Mapping is an intuitive tool which helps hearing care professionals better explain the benefits of amplification.
Getting Started
Speech Mapping is a Real Ear Aided Response (REAR) measurement; therefore the same equipment that is needed for a REAR is also needed. To start, follow the steps below.
Prepare the patient for REM
Measurement Steps
Figure 1: the Visible Speech Mapping screen
Note: If choosing DSLv.5, the MPO targets will automatically appear, since the UCL thresholds are always predicted from the audiogram. If choosing NAL-NL1 or NAL-NL2, the UCL thresholds need to be entered in the audiogram screen for the MPO targets to be generated. |
Counseling Elements in Visible Speech Mapping
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The Speech Spectrum: used to counsel regarding audibility.
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Using Live Speech Mapping or Environmental sounds.
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Counseling overlays.
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Unaided vs Aided.
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Speech Intelligibility Index. |
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Adaptive Feature example 1: Demonstrating Frequency Shifting.
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Adaptive feature example 2: Demonstrating Noise Reduction.
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Dynamic range.
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1For instructions on how to do the open fitting calibration, please refer to the REM Quick Guide
Introduction
The purpose of this Quick Guide is to provide guidelines on how to conduct basic technical measurements of hearing instruments using the HIT440 module for the Interacoustics Affinity 2.0 hearing aid analyzer.
Note: Hearing instruments needs to be in FULL ON GAIN MODE/TEST MODE in order to compare the results to the hearing aid manufacturers’ technical data sheets. Each hearing aid manufacturer has a different way of accessing this Test Mode. Please check with the hearing aid manufacturers for instructions on how to program the hearing aid into TEST MODE.
Setup
BTE hearing instrument
Required Items:
Positioning the BTE in the test chamber:
Place the coupler tube pointing straight forward and the microphone at the cross. (Multiple microphones: Place the half-way point between the microphones at the cross).
ITE/Open Fittings/Receiver in the ear
Required Items:
Positioning the ITE hearing instrument:
Place coupler at the back with hearing aid facing forward and the microphone at the cross. (For multiple microphones, rotate the hearing aid to get equal horizontal positioning of the mic inputs). Connect the ITE adaptor to the 2 cc coupler and attach the hearing aid using blue putty.
ITE pick-up coil test: For this particular test only: Position the coupler for maximum sensitivity of the coil.
Positioning the Open Fit/Receiver in the ear hearing instrument:
Connect the ITE adaptor to the 2 cc coupler. Remove the tip/dome from the hearing instrument and attach it to the ITE adaptor using the blue putty. Place the coupler tube pointing straight forward and the microphone at the cross.
Test procedure:
Comparing to the manufacturers specification sheets
Most hearing aid manufacturers use known international standards, such as the ANSI or IEC for their specification sheets. The same standard can usually be selected in the HIT440 software.
Testing for battery drain
For more information on HIT440, please refer to the Affinity 2.0 Additional Information document.
The purpose of this document is to provide a quick guide for the REM procedure stated by the British Society of Audiology (BSA) for the REM440 Real-Ear Measurement module in the Affinity2 and CallistoTM Suites. This Quick Guide will focus on the method and order of the REM measurements specified by this guideline.
Introduction
The BSA Clinical Practice Guidelines recommend using the NAL-NL1/NAL-NL2 fitting formulae when performing Adult hearing aid verification. The choice between the use of the REIG (insertion gain) or the REAR (aided response) is at the audiologists’ discretion as both methods are accepted verification methods. This Quick Guide assumes that the hearing aid has been programmed accordingly based on patients’ needs and hearing loss.
Preparation
Verification using Insertion Gain (REM Adult UK)
It is here that you will configure your prescription settings to acknowledge aspects of the patients amplification setup, i.e. venting, mono/binaural, compression method, whether you wish to base your target on their Bone values for mixed and conductive losses. etc.
Verification of Open Fittings (REM Adult Open Fit UK)
Open Fit Calibration steps:
Verification using the REAR protocol
For a more detailed description of how to use the REM440 module, please refer to the following documents:
The purpose of this document is to provide a quick guide for the Binaural REM feature found in the REM440 Real-Ear Measurement module in the Affinity 2.0 and Callisto™ Suites. This Quick Guide will focus on the method and order of performing measurements using this function.
Introduction
Interacoustics are pleased to announce the availability of a Binaural REM feature in the Affinity 2.0 and Callisto™ Suites. This feature will allow you to perform Real Ear Measures in a much faster procedure and allow you to view the activity in each ear simultaneously.
Preparation
Enter/Select an audiogram from Noah or from the AUD module. If no audiogram is entered or selected, no targets will be displayed.
To enable Binaural REM measurements in the REM module you will need to Right click on the ear selector icon. This will then show a binaural icon and a popup to alert the user when using this function.
Please note: when running measurements of this type you will only be using one reference microphone to monitor the signal from the speaker. This is the right microphone by default but it can be swapped to the left microphone by using the ‘use opposite reference microphone’ button.
It is also essential that the position of the patient in relation to the REM speaker is maintained at 0° as this will ensure that the same signal intensity is reaching each ear as they are equal distance from the speaker.
Connect probe tubes to the REM reference microphones.
Click on the Tube Calibration button and follow the instructions on the screen, this process ensures that the probe tube is made acoustically invisible – enabling an effective display of the actual gain achieved at the tympanic membrane by the hearing aid.
On running the calibration you will notice that in Binaural mode there is an automated procedure to calibrate both Left and Right REM tubes sequentially, without having to manually start each individually.
Position the patient approximately 0.5 metres from the REM loudspeaker.
Perform otoscopy to ensure the ear canal is clear.
Snap the REM headsets on the REM headband and place on patient’s ear.
Choose a relevant protocol to perform your verification; in this example the default ‘Adult Insertion Gain’ protocol has been used.
Note: For this example, an Insertion Gain method has been used to demonstrate the Binaural REM feature, however the feature is also compatible with protocols which perform this measurement in an Aided Response method.
Once you have chosen your protocol please configure your fitting prescription settings as per your fitting.
Place the REM tubes inside the patient’s ears and aim to use a marker of roughly 27mm on the probe tubes. This helps to get the open end of the tube in an optimum recording position (BSA, 2007).
Begin by running the REUR measurement, this is looking at the natural acoustics of your patients ear canals, it is performed with nothing in the patients ear canals apart from the probe tubes. Your response should peak around 2-3 kHz for a normal adult response (BSA, 2007). The shape of this measurement can also be used as a quality criteria for your probe placement, the measurement should intersect the
Horizontal axis (x-axis) at 6khz and must not be more negative than -5dB (BSA, 2007 & ISO, 2003).
Please place the hearing devices into your patient’s ears along with the probe tubes for the following measurements.
You will notice that there is a target in these measurements; in the next step it is shown how you can amend the output of the patient’s hearing devices to meet these targets.
Note: the default view for the Binaural REM feature is to have the left and right aided measure displayed side-by-side. However this can be swapped to an on-top comparison by pressing the button shown below, there is an example of this view below.
Note: Percentile analysis can also be performed in Binaural REM, you just need to enable this setting within your Aided Response measurements protocol. Once enabled, the test screen will show you the percentile range for your output, as shown below.
Note: Using this feature will remove your previous target allocation (i.e. NAL-NL2, DSLmi/o etc) from the opposite ear side, which you have not provided custom values for, because we cannot allow different prescription methods to be used on different ears independently.
Note: Binaural REM can also be used when fitting Open Fit type hearing aids. All this requires is for the ‘Open Fit Calibration’ to be run following the REUR measurement for the signal(s) you wish to use for the following measurements.
Note: Binaural REM can only be used with stimuli which do not require active referencing during the measurement. Therefore Binaural REM is not suitable for measurement with Warble Tone, Pink Noise, Random Noise, Pure tone and Narrowband Noise.
For a more detailed description of how to use the REM440 module, please refer to the following documents:
References
BSA (2007). Guidance on the use of Real Ear Measurement to verify the fitting of digital signal processing hearing aids. Reading, British Society of Audiology.
BS ISO 12124 (2001). Acoustics: Procedures for the Measurement of real-ear acoustical characteristics of hearing aids. Geneva, International Standards Organisation.
Introduction
The purpose of this Quick Guide is to describe how to verify FM transparency of FM system using the Interacoustics Affinity1 Hearing Aid Analyzer. FM Transparency can be defined as “The condition in which equal inputs to the FM and hearing aid microphones produce equal outputs from the hearing aid.”2 The verification method is according to the AAA Clinical Practice Guidelines for Remote Microphone Hearing Assistance Technologies for Children and Youth Birth to 21 Years. For more information, please refer to the AAA Guidelines.
The FM Transparency consists of 3 easy coupler measurements:
Verification Steps
NOTE: FM Transparency assumes that the hearing aid has already been programmed to match the targets, according to the patient’s hearing loss and patient needs. Therefore, there is no need to show targets on the screen. Targets and Fitting prescription information will not appear on the main screen when the FM transparency is chosen.
The FM Transparency setup guide will pop up when the above protocol is chosen, instructing the HCP on how to setup for FM Transparency verification3:
Step 1: HA Alone
Step 2: HA + Receiver
Note: the two curves should be very similar to each other
Step 3: FM Mic + HA
Note:
Step 4: Calculate the average difference
Example 1
*Average difference is less than 2 dB, therefore transparency is achieved
Example 2
*Average difference is less than 2 dB, therefore transparency is achieved
1To have access to the dedicated FM Transparency test, Affinity suite 2.4 or higher is needed.
2American Academy of Audiology (2011).
3The FM Transparency test is a coupler test, therefore the protocol will start up in coupler mode by default. Coupler mode is indicated by a hearing instrument attached to a coupler on the main screen.
References
American Academy of Audiology (April 2011). Clinical Practice Guidelines: Remote Microphone Hearing Assistance Technologies for Children and Youth Birth to 21 Years (includes supplement A).
Fernée, Ben Zalm (2012). FM Verification Made Easy
The purpose of this Quick Guide is to describe how to do real-ear verification of Ear Level FM systems (Oticon Amigo Star, Phonak iSense) with the Interacoustics Affinity 2.01 Hearing Aid Analyzer, using FM-specific targets.
The verification method is based on the AAA Clinical Practice Guidelines for Remote Microphone Hearing Assistance Technologies for Children and Youth Birth to 21 Years. For more information, please refer to the AAA Guidelines.
Introduction
Ear Level FM systems are intended to be used by patients who have normal or near-normal hearing and help increase the signal to noise ratio. They can be used, for example, in classroom settings for a child having learning difficulties or auditory processing disorders (APD). Typical use will include an ear-level FM receiver, coupled to a thin tube, in an open ear configuration. The steps below guide clinicians on how to perform straightforward real-ear verification of the ear level FM system, in order to verify the maximum output and the recommended volume setting for the FM receiver.
Verification Steps
From Noah or from the Affinity suite AUD screen, enter the audiogram. The audiogram will be within the range of normal/near normal.
Click on the REM tab.
Once in the REM screen, select the “Ear Level, FM only” protocol from the drop down list.
Place the FM transmitter microphone inside the test chamber, facing the reference microphone.
NOTE: The test box reference microphone is the active microphone
Close the lid of the test chamber.
Re-measure the RESR/MPO at user setting.
1Affinity software version 2.4 or higher is needed for Real Ear verification of ear level FM systems
References
American Academy of Audiology (April 2011). Clinical Practice Guidelines: Remote Microphone Hearing Assistance Technologies for Children and Youth Birth to 21 Years (includes supplement A).
Angelo, Kamilla & Fuglholt, Merethe L. (2013). Amigo Star. A New Ear-Level FM-Only Receiver. Pediatric Knowlegdge Brief.
Eiten, Leisha R. FM for Children, Chapter 7. Assessing Open Ear Edulink Fittings.
This Quick Guide is indented to provide information on how to conduct directional testing of hearing aids, using the REM440 module of the Affinity 2.0 and Callisto™ Software Suites.
Directionality Test using REM440
Directionality Test using Real Ear Measurements
To add the directionality test to an existing protocol:
1 If choosing US country defaults during the Affinity or Callisto software installation, the Directionality test will be available by default.
2 If selecting NO, you will have to create the protocol from scratch, which is beyond the scope of this document. For more info, please refer to the Instructions for Use document, Additional Info document or Quick Guide on Protocol Setup