University of Edinburgh

Audiology Refresher

Presented in February, 2002

Troubleshooting Hearing Aids

Hearing aid test box

Instructions for testing a post-aural hearing aid:

  1. Attach post-aural adapter to end of 2cc coupler.
  2. Place mic inside 2cc coupler.
  3. Check that alll internal settings of hearing aid are at manufacturer's settings and volume control is at maximum.
  4. Attach hearing aid to the coupler.
  5. Place coupler and hearing aid inside sound chamber with mic of hearing aid on the reference point. Switch on hearing aid.
  6. Close the lid of the sound chamber.
  7. With 90dB SPL IN, press the curve only button again.
  8. Change SPL IN to 60dB and press the curve button again.

These last two operations will give you print-outs which in most cases will be sufficient for checking against the manufacturer's specifications sheets. For your own records, you want to know how the hearing aid is performing at the settings your child wears it at.

  1. Adjust all internal settings to user settings and set volume to user volume.
  2. Place aid in sound changer as above and run at 60dB SPL IN.

If you keep this final print-out for future reference, then this is the only operation you require to perform every time you check the hearing aids. If future print-out match this one then the hearing aid is functioning normally.

To balance a personal FM system and a post-aural hearing aid:

  1. Attach a post-aural hearing aid to the coupler as above.
  2. With a 65dB SPL IN and a frequency of 1KHz, read the dB SPL OUT figure.
  3. Now attach the hearing aid to the FM system by means of the firect input lead and shoe.
  4. Place the transmitter in the sound chamber with the mic on the reference point.
  5. Place the post-aural hearing aid attached tot he receiver outside the test bos.
  6. With a 75dB SPL IN and a frequency of 1KHz, read the dB SPL OUT figure. Adjust the volume on the FM receiver until the dB SPL OUT figure is the same as it was for the hearing aid alone (that as; it was in point 2).

The systems is now balanced.