Hearing Aids & Music Settings

Modern hearing aids are complex devices, like tiny computers in the ear. They combine sampling, DSP, situational algorithms, dual mics for active directionality, level control and variable compression/expansion ratios across multiple frequency bands, noise reduction, feedback cancelling, frequency band shifting, multiple selectable programs, dynamic settings based on an instantaneous assessment of the current auditory situation, Bluetooth audio streaming, wireless control from smart devices, and more. They provide amplification that is both frequency and level dependent.

I recently corresponded with Neil Hockley, team leader for product management audiology at Bernafon AG, a noted Swiss manufacturer of hearing aids, who is instrumental in designing the features and algorithms that allow hearing aids to discriminate types of sounds.

He’s well versed in how speech and music differ, stating that, “Speech as a signal is quite predictable, so the systems in the hearing aid try to reduce the intrusiveness of non-speech sounds to improve intelligibility and comfort for the wearer. Music has some similarities to speech but also many differences and is a lot harder to detect reliably, regardless of genre.

“Some systems such as feedback and noise reduction may confuse music with the signal that they are trying to remove or clean up,” he continues. “The general guideline is to turn off these systems in order to reduce any interactions with music.”

The aforementioned Dr.Chasinisa foremost authority on music and hearing impairment, serving as the director of auditory research at the Musicians’ Clinics of Canada. He’s also written numerous articles and books including “Hearing Loss In Musicians, Prevention And Management,” and based on his experience and research, he’s developed recommendations for creating a hearing aid music setting.

First, the noise reduction and feedback suppression settings should be disabled. With sustained notes such as a flute or even a ringing guitar string, feedback suppression creates an annoying “fluttering” sound as the algorithm attempts to reduce what it perceived as feedback. Noise reduction can interfere with sharp, percussive sounds and the overall ambience of music. Second, the mic directionality should be set to omni so that it doesn’t randomly switch among sources.

Because of the higher levels and greater dynamics of music, the automatic gain control (AGC) input level before compression to the A/D converters should be raised to approximately 110 dB (because of the lower levels of speech the norm for most hearing aids is 95 dB). To accommodate the higher crest factor of music, he suggests lowering the output sound pressure level setting by 6 dB – similar to slightly lowering the input gain level on a mixer channel.

Enhancement Devices

In 2017, a new law in the U.S. authorized over-the-counter hearing aids, though since the FDA (Food and Drug Administration) has three years to finalize the rules, as of yet there’s no exact definition of those devices. Effectively, personal sound amplification products (PSAP)such as the Etymotic Bean and others have potentially been reclassified as hearing aids, at least for those individuals with mild to moderate and typical high-frequency loss.

And just this past October, the FDA gave permission to Bose to market a hearing aid to individuals with “perceived mild to moderate hearing impairment,” with the ability for users to fit, program, and control these hearing aids on their own via smart devices.

Though this device is not yet available, I did preview a sample of the Bose Hearphones, which are presented as an aid to understanding conversation in noisy environments as well as being noise-cancelling wireless headphones for music and other streamed audio.

Hearphones, when paired and controlled with a smartphone app, allow users to select from three mic settings – “focused” cardioid, half-space, and omni, as well as to adjust the “World Volume” or outside sound pickup from zero to full, emphasize bass or treble to roughly compensate for frequency losses, and send different levels to each ear if one is less sensitive.

Wearing them at the Monterey Jazz Festival for a show, I found that they sounded quite natural and had full fidelity, also helping to fill in some missing frequency ranges due to my hearing loss. On YouTube I discovered a video of an audiologist who tested them and found that with some fiddling with the settings, he could approximate a corrective curve similar to that of a hearing aid for mild losses.

I ran into drummer Akira Tana at the festival as he was finishing a performance and noted that he was wearing hearing aids. He mentioned that the next week he would be testing some prototype aids from startup Concha Labs, and he helped put me in touch with company CEO Amy Li.

In a conversation with her, she explained that a key innovation is a methodology for hearing measurement and fitting that is much more precise and prescriptive – akin to the “which is better” comparisons used when prescribing glasses. Although not yet available as a product, the goal is to make hearing evaluation much more accurate and user-friendly, significantly lower the price of quality hearing aids, and provide individuals with the means to make more of their own adjustments.