Hearing Aid Transition (HAT)

What is the hearing aid transition (HAT) test?

We understand you have new patients who attend with their existing hearing aid and sound preferences, but you do not have their historic fitting sessions to be able to relay those benefits and continue that satisfaction.

The Hearing aid transition test has been created to help you to copy fine tuning preferences from hearing aids which you do not have previous sessions stored for. This can be especially useful in the following scenarios: 

1. Upgrading a patient’s hearing aid to a newer one where you do not have historic sessions
2. Upgrading a patient’s hearing aid to another brand compared to their current hearing aid
3. Understanding proprietary target algorithms

Preparation

1. Enter/Select an audiogram from Noah or from the AUD module. If no audiogram is entered or selected, no independent targets will be displayed.
2. Enter the REM module and choose a test protocol which contains the Hearing Aid Transition Test. When prompted choose settings for your independent target algorithm, i.e. NAL-NL1, NAL-NL2 or DSL v.5.0.
   
3. Connect probe tubes to the REM reference microphones.
4. 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. 
   
5. Position the patient approximately 0.5 metres from the REM loudspeaker.
6. Perform otoscopy to ensure the ear canal is clear.
7. 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).
8. Begin by running the REUR measurement, this is looking at the natural acoustics of your patient’s ear canals, it is performed with nothing in the patient’s ear canals apart from the probe tubes. Your response should peak around 2-3 kHz for a normal adult response (BSA, 2018). The shape of this measurement can also be used as a quality criterium for your probe placement, the measurement should intersect the Horizontal axis (x-axis) at 6khz and must not be more negative than -5dB (BSA, 2018 & ISO, 2003). 
   
9. Insert the patients current hearing aid.
10. Run the HAT test measurement. 
    
    On running the measurement, the system will measure and show the outputs for all three measurement intensities alongside your standard target algorithm. 
    
    Once this measurement has completed you can compare these measurements to the standard target algorithms you had selected in step 2.
    
    The measurements made will be stored as new target selections which can be chosen on the right of the screen. They will be stored under Hearing Aid transition.
    
    
11. You can now proceed to position the new hearing aid on your patient’s ear, be very careful when doing this to maintain the probe tube position.
12. You are now able to proceed your fitting for the following REAR measurements which correspond to the intensity levels of the measurements achieved in the HAT test. These are your new fitting targets. 
    
    Note: the HAT test can only be run using the REAR measurement method. 
    
    Note: the possibility to change the target algorithm is to allow you to give multiple fine-tuning configurations to your patient’s new hearing aid. For example, this will allow them to have different programs on their new hearing aid, Program 1: the same gain characteristics as their old aid and Program 2: gain characteristics according to a NAL-NL2 fitting prescription.
    
    
13. Once you have programmed your hearing devices so that the patient is happy and have counselled them involving their opinions in the amplification of their hearing devices you can save and close the Suite and finish the session. This is done by pressing the ‘Save and Exit’ button
    
    Note: he HAT test can also be applied during coupler fitting, just ensure an RECD is applied in advance of running the HAT test and the following REAR measurements. 
    
    Note: Ensure correct precautions are taken when fitting hearing aids with leaking ear couplings by running an Open Fit Calibration measurement where necessary. 

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.