Ask Dr. Abonso
1. Can Hearing Aids Really Filter Out Background Noise?

Dr. Abonso: Well, yes they can.

Suspicious Consumer: Isn't that a good thing?

Dr. Abonso: Well, not usually. In fact, some of the worst hearing aids filter out the most noise.

Suspicious Consumer: Filtering out the noise still sounds good to me, what's wrong?

Dr. Abonso: Those hearing aids were mistakenly designed to replace the brain, or more accurately to replace the brain's ability to separate speech and noise. It's a bad idea and it doesn't work. Can you tell me what hearing aid could be smart enough at a party to know that Fred's voice was speech but Nancy's, George's, Sarah's, and Mark's voices were noise? And thirty seconds later that Nancy's voice was speech and the rest were noise?

Suspicious Consumer: Hey, who's asking the questions here? WHAT IS WRONG WITH FILTERING OUT THE NOISE?

Dr. Abonso: You filter out speech cues at the same time. Filtering out low-frequency noise is popular in certain widely advertised types of circuits, for example, but they filter out low-frequency speech cues at the same time. The circuit can't separate low-frequency speech from low-frequency noise, only the brain can. These circuits starve the brain of some of the speech cues it needs do its job properly.

Suspicious Consumer: Is there any hope?

Dr. Abonso: Yes, restore all speech sounds with a high-fidelity hearing aid adjusted to compensate for the loss in your hearing sensitivity. These hearing aids make almost everything audible -- speech and noise -- so your brain can do its job.

Suspicious Consumer: This is 1993. Aren't all hearing aids high fidelity now?

Dr. Abonso: Unfortunately not. Some hearing aids still sound tinny and distorted like the old pocket radios. The very best hearing aids, however, now have low distortion even when people are screaming at baseball games, and a full frequency reproduction like your home stereo.

Suspicious Consumer: OK, tell me which ones?

Dr. Abonso: Well, some 30 manufacturers use a new "K-AMP" circuit that provides high-fidelity amplification. More expensive, but also more effective in some difficult cases, are the RESOUND and ENSONIQ programmable hearing aids.

Suspicious Consumer: So I just get high-fidelity hearing aids and the problem is solved just like that?

Dr. Abonso: Yes and no. It is not the instant solution, politicians love to promise. You may need to go through a relearning period

Suspicious Consumer: How long does that take?

Dr. Abonso: Often four to six weeks. That seems to be the time required for the brain to learn (relearn) how to recognize common interfering sounds and put them into the background. At the end of this adaptation period, you will still hear the noises, but they will interfere much less with your ability to carry on a conversation at a restaurant, party, baseball game (really good hearing aids are required there), etc.

© 1993

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