Performing a Real Ear Measurement (REAR)

10 mins
04 June 2020

Hello and welcome. This video explains the process required when fitting hearing aids on a patient's ear using an Affinity Compact.


REM process

The on-ear fitting process involves several steps in this order:

  1. Selection of audiometry
  2. Choosing the correct target
  3. Probe tube placement
  4. Real ear unaided gain (REUG)
  5. Real ear occluded gain (REOG)
  6. Calibrate for open fit (optional)
  7. Aided measurements and target match


Step 1: Selection of audiometry

First of all, in your patient management system, select the patient you wish to fit your hearing aids for and launch the Affinity Suite software. Your software will start up in the audiometry screen and your audiometry is your starting point for hearing aid fitting. It should be performed to the best detail to ensure the best fitting and reduce returns from your patients. You can choose to perform the audiometry from scratch or select the audiometry session that you wish to base your fitting on.


Step 2: Choosing the correct target

On launching the REM module of your software and selecting your test protocol, you'll be prompted to select the fitting prescription. There is a lot of choice surrounding the fitting prescription but we recommend choosing the NAL or DSL algorithms as these are both evidence-based targets which give a good starting point to base your fitting around.


Step 3: Probe tube placement

Your probe tube is your measurement reference point for your fitting and correct placement ensures quality measurements. Ahead of placement, you should run the tube calibration process to ensure your equipment is correctly prepared for the following measurements.

You should follow these steps to ensure a good probe tube placement:

  1. Good otoscopy to ensure you know the shape of the patient's ear canal and observe for any obstacles like wax. You can also perform otoscopy once the tube has been inserted to get a better placement after readjustment.
  2. Move your marker on your probe tube to 28 or 30 millimeters depending on the patient's gender. This ensures that you aren't over-inserting the probe into your patient's ear.
  3. Once the probe is placed, observe your REUG to assess your probe placement quality. If you're not within 5 dB of the 0 dB mark at 6 kilohertz, reassess your probe tube placement.


Step 4: Real ear unaided gain (REUG)

Your REUG measurement allows you to measure the effects of the unamplified ear. This measurement is useful for assessing probe tube placement and also for assessing whether to run a calibrate for open fit in comparison with the REOG measure.


Step 5: Real ear occluded gain (REOG)

The REOG is a measure of the occluded ear. To do this, first insert the hearing aid into the patient's ear and ensure that it is muted or off. Then run your measurement. This measurement can be compared against the REUG measurement and if it looks the same, then you will need to perform the calibrate for open fit measurement. If there is a difference, then you don't need to take any further actions and you can move on to your aided measurements.


Step 6: Calibrate for open fit (optional)

The calibrate for open fit measurement performs a process to ensure accuracy when fitting hearing aids which would leak sound. These are typically open fits or molds with large vents. Leaving your hearing aid muted, run the calibrate for open fit measurement with the patient placed in the position they will be in for the remainder of the measurements.

This process should be done for each stimulus you wish to use for your aided measurements. The measurement results and the curves shown are not relevant but the process of performing this prepares the system for the aided measurements.


Step 7: Aided measurements and target match

You can now switch on the hearing aid and begin to fit. It's advised you run three different stimuli levels: 65, 50 and 80 dB. This ensures that you're assessing the hearing aid at different levels of intensity. On running the different stimuli, you should alter the gain trimmers in your hearing aid software to ensure target match.

You can use the Delta Values feature in your Affinity Suite to ensure a good target match. Once the sufficient target match has been achieved at all three levels, the objective aspect of the fitting has been completed. You should now move on to counseling the patient around the amplification and sound they're receiving and include their preferences within the fitting.


Dennis Mistry
Dennis Mistry, BSc (Hons) Audiology, graduated from Aston University in 2011. Dennis is a former Clinical Product Manager at Interacoustics, and was part of the Hearing Aid Fitting product management team.

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