Audiologists are understandably concerned with things that they can do something about. Typically this means adjusting the programming software to the extent that they can in order to optimize a signal for speech and for music. In some cases this is all that can be offered to a particular client. This isn’t a criticism, but just a description of the current clinical reality. There is only so much an audiologist can do, given the limitations of any particular hearing aid and the limitations of a damaged auditory system.
Audiologists are working hard to keep the lines open between the hearing aid manufacturers (and their researchers and engineers) and their clients. Go to any large audiology conference and you will typically see packed audiences for talks on hearing aids and future hearing aid technologies.
In previous blogs I have discussed some limitations with hearing aids for music and noted that these are typically hardware related and not things that ‘simple’ software adjustments can remedy. If a particular hearing aid cannot handle high level inputs typical of many forms of music, then no amount of software programming adjustment will improve things.
Since there are now some technologies available in hearing aids to handle the higher level inputs of music, the ‘best’ hearing aid for music is one that has certain ergonomic or music-specific features.
Several weeks ago, I posed a question to the Association of Adult Musicians with Hearing Loss the following question- what things would the musician readers of this listserv put on their hearing aid wish list? The AAMHL is a wonderful group of volunteers made up of hard of hearing and deafened musicians (many who wear hearing aids and/or cochlear implants), audiologists, and other researchers and clinicians who are interested in the various strategies to improve the listening and the playing of music. They even came out with a book last year entitled Making Music with a Hearing Loss (edited by Cherisse W. Miller, ISBN # 978-1-45658-638-6) with an entire chapter entitled “Personal Stories and Strategies”. These strategies are descriptions of techniques that have resolved difficulties in any number of musical environments. The book can be obtained through the AAMHL website.
But back to the question at hand: What things would the musicians like to see in hearing aids? Specifically, if we can resolve some of the ‘front end’ problems and ensure that the hearing aid does not distort with high level musical inputs, what other things should be available to the hearing aid user for music?
The response was great and some of the comments could easily be implemented today in the hearing aid industry. Following are four of the comments (in bold) with some of my responses below in italics:
Let’s make the upper limit 130 dB or so, so all percussive sounds get processed without any distortion.
Modern hearing aid microphones can only handle about 115 dB SPL before distortion. This has been the case since about 1988. Drums can transmit levels on the order of 130 dB, but that would be 130 dB ‘peak’ with much of its energy being of a lower level (less than 115 dB SPL) and its spectral energy being at, and above, the top octave of the of the piano keyboard (typically above 2000 Hz). There would indeed be some distortion with even the best hearing aid microphone, but I wonder if the distortion would be audible to someone with a high frequency hearing loss in the 2000-4000 Hz region. Only the percussionist would be subject to the 130 dB peak sound level, and it seems that at that level, no amplification would be required in any event. Removing the hearing aids and wearing appropriate hearing protection (e.g. ER-25 from www.etymotic.com) would be better. I would suspect that the sound of the drum cymbals and rim shots would be clearer sounding with hearing protection than with amplification.
It should be capable of full-range reproduction, at least from 40 Hz to 16 kHz.
I agree that the bandwidth should be as wide as possible, and I would make this same suggestion for speech as well- at least for the upper end of the spectrum. If a hearing aid is capable of transducing sound energy up to 16 kHz, and the gain is sufficient for a hard of hearing person, then there is no reason to have this only for music. Speech has some sibilant consonants that have their energy in this rarefied region. In contrast, there is no speech energy below the fundamental frequency- typically 100 Hz for the lowest of men’s voices, so there is no reason to amplify the region below 100 Hz (or even 200 Hz in most situations).
Music does have many fundamental notes below 100 Hz, but I am not sure that we need any amplification here. In speech, and I suspect in music, it is the difference between the successive harmonics that define pitch and not the value of the harmonic itself. For example, a man who has a fundamental frequency of 125 Hz (such as myself) has a pitch of 125 Hz because the next harmonic is at 250 Hz (and then 375 Hz 500 Hz, 625 Hz,…). It is the difference between 125 Hz and 250 Hz (also 125 Hz) that defines the pitch, and although the difference is 125 Hz, this “difference” can be seen as easily between 500 Hz and 625 Hz, which is well within the amplified region. For those who want more information on this phenomenon, type “The Missing Fundamental” into any search engine or look in any introductory textbook on psychoacoustics. Also, in many hearing aid fittings, the very low (long wavelength) frequencies enter the ear directly bypassing the hearing aid either through a vent in the hearing aid or through the earmold itself. Therefore, I am skeptical about whether a hearing aid that indeed transduces sound down to 40 Hz would be better than one with a more “conventional” frequency response.
Real-time user programmability in real-world situations from a smartphone.
I strongly agree with this request by our musician clients, but I do have one caveat. For anyone who has played around with equalization (or EQ, as our audio colleagues may call it), it doesn’t take much fiddling around to completely screw up the sound. Too much freedom in the programmability realm may be a problem. I would suspect that if the musician were given control over some compression parameters and not frequency response, then everyone would be happier.
A QUICK push button control that can enable hearing aids for listening to conductor comments vs. music.
This is something that most of my own musician clients have asked for. An “override” button that using one setting, they can listen to the conductor, while at another setting it can be optimized for their music. This can be an actual mechanical button or it can be implemented by a wireless (Bluetooth?) technique. This is something that modern hearing aids do offer, but sometimes offer it “too much”. A hearing aid set up for two programs (and not four or five) would allow the musician to toggle between program 1 (conductor) and program 2 (music) without having to cycle through the TV, speech-in-noise, and telephone programs first. Perhaps, sometimes less is more.
