It will come as no surprise to regular readers of this magazine that one of the main reasons I got into the field of hearing healthcare was music. It is a great passion of mine, something I consider vital to my psychological and spiritual well being. So I understand the impact that hearing loss can have on people like myself, for whom music is a critical part of their life, be they musicians or fans. Because of that, I’ve dedicated myself to helping those with hearing loss recapture their ability to properly appreciate the music they love. But it is often no easy task. And with greater degrees of hearing loss, I may never be able to approximate like it was.
The vast majority of hearing loss is due to damage to the inner ear or cochlea, or more specifically, to the nerve cells of the cochlea. There are two types of nerve cells in the cochlea that give us our amazing hearing abilities, what are known as inner hair cells (IHC) and outer hair cells (OHC). The IHC are the cells that send the actual electrical signal to the brain. The OHC, ‘tune’ our ears and work as tiny internal biological amplifiers. When I refer to tuning, I’m speaking about pitch perception. Pitch is the term used to describe the subjective perception of a sound (i.e. bass vs. treble or baritone vs. soprano), and is related to the physical measurement of frequency–Hertz or Hz (not the car rental company).
The healthy ear can detect pretty small changes in pitch and loudness. Nerve hearing loss decreases the ability to detect softer sounds and changes how the brain perceives sound, affecting both loudness and pitch perception. For speech understanding, this manifests as both a drop in volume and clarity. This drop in clarity stems from not only not getting enough volume for the most important sounds for speech understanding (soft, high frequency), but also from the distortion of the coded information to the brain. There can also be an abnormal growth in subjective loudness, a phenomena we refer to as recruitment. Sounds are subjectively louder than they would be for a person with normal hearing. With music, there’s also the expected drop in volume for particular musical notes, along with distorted coding of those musical notes.
Though the causes for/issues associated with nerve hearing loss for speech and music perception are similar, the way I address those two issues with amplification (i.e. hearing aids) is very different. Because of the anatomy and physiology of the auditory system, hearing loss typically affects higher frequencies first, particularly the most critical area for speech understanding between 2-6 kHz. So when I’m programming hearing aids for speech perception, I am doing so to maximize my patients’ ability to hear and use information above 2 kHz while maintaining appropriate loudness perception & comfort. I take into account the changes in loudness perception so that soft sounds aren’t too soft and loud sounds aren’t too loud. This is achieved using a form of sound processing known as wide dynamic range compression (WDRC) processing. As the volume of the sound coming into the hearing aid goes up, the amount of volume we add goes down. For speech, changing the relative volume of one speech sound to another does not change the meaning.
But for music, changing the relative volume of one note to another DOES affect the ‘meaning’ (if you will) of the music. So I have to adjust the hearing aid so that it processes in a more ‘linear’ fashion. In addition, the frequency area we want to emphasize for music is very different from that of speech. Even though a standard piano has keys with notes a little over 4 kHz, the vast majority of notes are below 2 kHz. So when I program hearing aids for the best reproduction of music, I’m emphaszing 2 kHz and below. The opposite of that for speech.
There are other factors that will play (pun intended) into how well hearing aids do for music, but I wanted to give you a small sense of the intricacies & details associated with the best hearing aid fittings so that you understand the importance of working with highly trained hearing healthcare professionals.
Please continue to look out for one another by wearing facemasks and following all other public health guidelines. Please continue to support your community by supporting local businesses. And please vote! We get through all of this working together! Wishing all of you health and/or healing
