We don’t always need to understand the problem in order to solve it

From time to time (actually, almost daily), I receive inquiries from those in the performing arts who have either heard me give a talk or come across a paper on the Internet.  I usually begin my response with “Talk to your audiologist” or if they appear to be frustrated “I would be happy to chat with your audiologist if they are amenable to that.” I would never try to impose my suggestions and thoughts on someone who is in the midst of a clinical situation.  Their own hearing health care professional undoubtedly knows much more about this situation than I do, and the last thing I would want is for a client to walk into my clinic with a piece of paper that tells me what I should do.

Having dispensed with this tirade, here is an email that I received the other day. It points to a possible solution, but one that perhaps we do not need to figure out to solve.  As a quick summary, this hard-of-hearing musician has figured out how to make his instrument sound good by holding it in a weird position.  All the audiologist needs to do is try to figure out what makes the weird position so good and replicate that in the hearing aid prescription. We don’t need to ask “why,” just “how.” Parts of his emails are reproduced below in italics and my comments are in bold text.

Q:  I’ve recently lost some low-frequency hearing in one ear (SHL), and am exploring hearing aids. One  issue I have is that I can’t seem to find a hearing aid that will boost sounds in the low frequencies (below 250 Hz). I’m a classical guitarist and the lowest string (E) starts at 82.4 Hz…  I also mix and produce music in my studio so this sudden development with my hearing loss is quite disturbing to me. What do you recommend for musicians who are looking for a hearing aid that will not sound artificial and has a wide spectrum of frequencies available to boost ?

My response centers on the “missing fundamental” and why this person doesn’t really need a hearing aid that extends into the lower frequency region:

A:  Given your hearing loss you do require some amplification at 250 and 500 Hz (and perhaps also at 1000 Hz, even if your hearing thresholds are normal at that frequency).  There are no really good hearing aid prescription formulae for low-frequency loss, so it may take a bit of trial and error with your audiologist. 

 I don’t think that you need very low frequency amplification (below 200 Hz).  Most of what we hear when we say we hear low A on the piano is the harmonic structure. Pitch is not equal to the fundamental frequency of the note.  Pitch is equal to the “difference” between any two successive harmonics (which for half wavelength resonators such as the piano and the guitar) is the same number value (in Hz) as the fundamental.  This phenomenon is called the missing fundamental and explains why we can hear someone’s pitch on the telephone even though phones only transmit between 340 Hz and 3400 Hz.  The fundamental frequency is below 340 Hz, but we have no trouble hearing someone’s pitch.

I feel that the same thing applies to the region below 250 Hz, so I think that most commercially available hearing aids are possible for you.

I know that there is a controversy about extending the response of a hearing aid down to the left side of the piano keyboard for music, but my opinion is that this is not required; our brains will fill in the missing information where needed.  Also, an appropriately vented (or even non-occluding) hearing aid coupling will allow the very low-frequency sounds to get through unamplified, and unattenuated.

And his response to me was:

Q:  I think you are on to something regarding the fundamental frequency. By my audiogram, you would think boosting 250 to 1000 Hz would help. However, when I play open guitar strings in the 196 to 261-Hz range (middle C), I hear distortion. If I put my ear right up to the strings and play those same notes, the distortion lessens almost completely.

Why I think I’ve lost the low frequencies (bottom end) is if I play the guitar with my head turned looking towards the guitar neck (bad /right ear is now picking up most sound from strings), I hear a small thin sound. As I turn my head 180 degrees away from looking at the guitar neck, the tone becomes warm and full. Big bass boost with the good ear now picking up most of the string sound.

I woke up one morning with a blocked ear, tones sounding different in pitch between both ears, speech sounding a little robotic. Four weeks later the third audiogram showed hearing loss. At first it was diagnosed as fluid in the cochlea, then when the ECOG came out normal for both ears for fluid pressure (i.e., Menieres Syndrome), it was said to be inflammation, as steroids seemed to have helped.

I will try anything & everything to try to recover what I’ve lost. It may be considered mild hearing loss with regards to speech, but certainly is anything but that with regards to music.

 And my final response was:

A:  I would suggest that you share your comments about how you can hear the guitar better with certain head positions with your audiologist. Also, bring your guitar to your audiology appointment.  He (or she) can place a small probe microphone in your ear canal and see the exact sound level that is optimal for you. The audiologist can then set up a hearing aid with exactly that sound distribution. This is a little like doing an “end run” around the problem.  We don’t need to know why the guitar sounds good in a certain position- only what exactly is happening when you feel that the guitar does sound good and this can be replicated with a hearing aid.

This is a case where we don’t need to figure out what is going on..  We simply need to measure with a probe microphone what is happening in his ear canal when he is hearing his guitar better, and then program a hearing aid to accomplish this response.

About Marshall Chasin

Marshall Chasin, AuD, is a clinical and research audiologist who has a special interest in the prevention of hearing loss for musicians, as well as the treatment of those who have hearing loss. I have other special interests such as clarinet and karate, but those may come out in the blog over time.