by Neil Bauman, Ph.D.
A man wrote:
My question is about hearing aid effectiveness. I notice that some people talk about having hearing aids but still having problems hearing. At the price that hearing aids go for, while I don’t expect to have Superman’s hearing, I thought I would be getting rid of the mumbles. I would expect issues such as background noise, certain sounds amplified that you don’t want to hear etc, but I do expect to understand what people are saying at a conversational level, even on the phone. Why are people having problems understanding conversational speech?
That is a good question. Let me explain. You need to realize that when hearing loss occurs, a number of things happen.
First, obviously, there is a hearing loss. If this was all that happened, then hearing aids could easily fix this problem by providing exactly the right amount of amplification at each frequency to make up for the hearing loss.
But this is not all that happens. Coupled with hearing loss is a decrease in the ability to discriminate between similar sounds. Thus speech, even when at a comfortably loud level, sounds “fuzzy” or “muddy”. You hear people talking, but just can’t quite understand what they are saying. Amplifying this just makes louder “fuzzy”. It does little to make it clearer.
It’s analogous to wearing glasses. If your glasses are ground wrong (fuzzy) you see everything fuzzy. But if your glasses are ground correctly, you expect to see clearly. But this does not always happen because the “fuzzy” may be in the lens of your eye. The light passes clearly though your glasses, but then gets “messed up” as it passes through your “fuzzy” lens.
This is exactly what happens with hearing. The amplified sounds may pass clearly through your hearing aids–but then they hit the “fuzzy” cochlea and you hear distorted speech. This is not the fault of the hearing aids, but of a damaged auditory system.
This is why we call hearing aids “hearing aids“—they are aids to better hearing, not the cure for poor hearing.
The worse your discrimination scores, the less you can expect hearing aids alone to help you. For example, with my hearing aids, my discrimination is approximately 62% or so. This means that out of every 100 words spoken, and when amplified properly for my hearing loss, I still don’t understand 38 of them. That is why I always speechread at the same time—to fill in the “fuzzy” words.