Listen to Coupler/Probe Microphones

Introduction

It can sometimes be difficult to understand feedback from your patient regarding how their hearing aid sounds. The Affinity Compact has a handy feature which allows you to listen directly to the probe tube microphone or coupler microphone to hear exactly what the hearing aid is doing.

Preparation

1. Enter your REM module as you would normally. Ensure you have a monitor headset plugged into your Affinity Compact, the socket which this is connected to is shown below. 
   
2. Connect probe tubes to the REM reference microphones.
3. 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. 
   
4. Position the patient approximately 0.5 metres from the REM loudspeaker.
5. Perform otoscopy to ensure the ear canal is clear.
6. Place the REM tubes inside the patient’s ears and aim to use a marker of roughly 28mm (female) and 30mm (male) on the probe tubes. This helps to get the open end of the tube in an optimum recording position (BSA, 2018).
7. Choose the protocol you would normally use in your system.
8. Enable the Listen to Coupler/Listen to Probe Microphone feature by clicking on the ‘Monitor’ check box on the left panel. You will then need to manually adjust the level up to find a suitable listening level. 
   
   Note: The level will default to zero whenever it is enabled to prevent accidental listening at loud intensity levels.
   
   The microphone which you will listen to is based on how your system has been configured to perform measurements. For example, when the right ear is selected during an REAR measurement using the insitu REM headset, the sound played to the probe microphone in the patients’ right ear will be monitored. If binaural is selected then the left probe will come through the left monitor headset and vice versa. 
   
   This can also work for coupler measurements when measurements are being performed in the coupler.
   
   Note: The monitor function will only work when a measurement is running and once the referencing procedure has completed. To be able to listen live without a stimulus then it is advised you perform a Visible speech mapping measurement and use a ‘Live Voice’ stimulus.
   
   
9. Complete your fitting session as you would normally according to your protocol.
   
   Note: This feature is a very effective tool for including the patients supporting relative in their appointment or even for further understanding patient feedback during the fitting.
   
   Note: This feature can also be used in the HIT module to listen in to the hearing aids performance when performing HIT testing. An example of its application could be to hear minor distortions which may occur due to change in the applied stimuli. 
   
   

References

BSA (2018). Guidance on the verification of hearing devices using probe microphone measurements. Reading, British Society of Audiology. Available online: http://www.thebsa.org.uk/wpcontent/uploads/2018/05/REMS-2018.pdf [Accessed: 02/05/2019 10:39].

BS ISO 12124 (2001). Acoustics: Procedures for the Measurement of real-ear acoustical characteristics of hearing aids. Geneva, International Standards Organisation.