Do you turn your hearing aid to 'T' before trying to use the telephone?
We suspect that you are not doing this.
If the hearing aid is left on microphone 'M' and the handset earpiece is held near the hearing aid, the surface of the earpiece will then reflect any sound leaking from the hearing into the hearing aid microphone thus causing howl round feedback - your whistling noise.
A hearing aid is set to match the hearing loss of the user. Not only for volume of sound but also with 'frequency shape' to help counter the hearing loss. Hearing loss is rarely a flat loss so using an amplified telephone will never be as good as using a hearing aid compatible telephone and a correctly set up hearing aid.
To use a hearing aid with a telephone:
1) Make sure you have a hearing aid compatible telephone.
2) Turn hearing aid to 'T'.
3) Use telephone as normal.
If you have not had the use of your hearing aid 'T' pickup shown to you we would suggest making an appointment with your hearing aid clinic for them to demonstrate the advantages of it's use.
