A question that comes up frequently at our clinic, and I’m sure is asked by many people seeking treatment for their hearing loss, is - how many channels in a hearing aid are enough? Isn’t more better?
First, let’s get some terminology straight…
With respect to hearing aids, frequency regions are divided into “bands” that can be adjusted for the appropriate amount of volume ( or “gain”) depending on a person’s hearing pattern. Research studies have shown that hearing aids that have between 4 and 15 bands are adequate to fit the vast majority of hearing loss patterns. Generally, the steeper the slope of the hearing loss, the more benefit will be achieved with more bands – up to perhaps 15 or 18.
“Channels” in a hearing aid are processing filters that can automatically adjust for compression (reduction of loud sounds), noise, acoustic feedback, microphone directionality and other functions. Theoretically, the more channels a hearing aid would have, the more precisely it would suppress feedback, differentiate speech from noise, compress unwanted loud sounds, etc. -Right?
Well, there is a point of diminishing returns when it comes to the number of channels and measurable or perceived benefit. Processing functions for all those extra channels takes time and power and can lead to spectral distortion and time delays. At a certain point, there is at best, no additional benefit, and at worst, degraded sound quality and clarity.
So there is a balance to be determined, and it is important to have certain information at hand in order to determine the proper balance. A comprehensive audiogram with hearing thresholds, loudness tolerance levels, speech-in-noise performance, a review of a patient’s listening environments and complexity demands – all of these come into play when making a decision on how many “channels” and “bands” are needed to get the job done.