by Neil Bauman, Ph.D.
A man explained:
I always wondered what the ‘immediate after-whoosh’ was while wearing my hearing aids, and was enlightened to find out that it was something called ‘entrainment’, which only those who wear hearing aids hear. Are there any techniques or tips for listening through, or coping with, entrainment, or is it something I’ll just have to get used to whenever I wear my hearing aids?
Probably “entrainment” is a new word to most readers. It’s certainly not a word that is bandied about in casual speech!
Entrainment is a relatively recent phenomenon as it applies to hearing aids since it only occurs in hearing aids that have anti-feedback circuitry in them. Most hearing aids manufactured in the past 10 years or so have anti-feedback circuits. As a result, entrainment may actually be quite common now. I know it happens with my hearing aids under certain conditions.
What happens is that when a sound (tone) is held for more than a fraction of a second, the anti-feedback circuit in your hearing aids thinks that the hearing aid is beginning to feedback (whistle) and so it attempts to squelch that sound. This often happens when you are listening to music for example. As I understand it, the anti-feedback circuitry and the hearing aid’s amplifier both try to synchronize the tone with each other, thus causing the sound to be prolonged (which greatly distorts the original sound).
I hear that with my hearing aids if I listen to music with my speech program. When listening to music, I need to switch to my music program where the anti-feedback circuitry is turned off. This immediately eliminates any entrainment.