by Neil Bauman, Ph.D.
A lady asked,
My son is 5 years old and will be entering Kindergarten in the fall. We are currently trying to fit him with new hearing aids. His left ear has reverse slope loss. 65db @ 250 60db @ 500, 45 @ 1000, 25 @ 2000-8000. His current ear mold has a vent to allow natural high sounds to enter.
His right ear has the more common ski-slope. loss from 40 @ 500 all the way to 110 @ 4000 The right ear mold is completely closed.
My audiologist told me that in order to obtain the correct amount of low frequency amplification in the left ear she would need to close the mold. Somehow that seems less than perfect and doesn’t sit right with me.
It may be theoretically true that he needs to have an ear mold with no vent so lots of low frequency amplification can be pumped into his left ear, but it doesn’t work out in practice. This is because people with reverse slope hearing loss don’t want or need all the low frequency sounds. Amplifying these sounds to “normal” is actually counterproductive. This is because it makes it so we can’t understand speech as well. All the research shows, and those of us with reverse slope losses firmly declare, that we need less low frequency amplification than what is theoretically true.
Few audiologists apparently know how to properly fit people with reverse slope losses—so they go by the theory—and it is wrong. All the adults with reverse slope losses that I have heard from have told me the same story—their audiologists insist on setting their aids wrong to begin with (too much low frequency amplification and not enough in the high frequencies). They insisted that their audiologists adjust them in the reverse before they were happy.
She then asks: “Do you agree that it may be the only way to achieve help in the low frequencies? Does it matter that the mold had an opening and now it will need to be closed but that the high frequencies have good hearing?”
Here’s the problem. With reverse slope losses, we hear the highs. When we wear hearing aids, there are only two ways we can do this. One is if the ear molds have large vent holes. The second way is if the hearing aids are wide band aids (and almost none are) and amplify up to 16,000 Hz or so. (Most hearing aids only amplify up to 6,000 Hz or so.) Thus, by wearing hearing aids, we hear less than we should—unless provision is made for us to hear the high and very high frequency sounds upon which we so much depend.
You would do well to read my unabridged article on the subject of reverse slope hearing loss, The Bizarre World of Extreme Reverse-Slope (or Low Frequency Hearing Loss—especially the final section—which gives tips for properly setting hearing aids for reverse slope losses. Be warned, it’s 32 pages long—but it is very easy to read.