The type of sound processing that modern hearings aids provide to make speech more understandable for wearers may also make music enjoyment more difficult, according to a new study by the University of Colorado Boulder.
The findings, published in the journal Ear and Hearing, suggest that less sophisticated hearing aids might actually be more compatible with listening to music, especially recorded music that has itself been processed to change the way it sounds.
鈥淗earing aids have gotten very advanced at processing sounds to make speech more understandable,鈥� said Naomi Croghan, who led the study as a doctoral student at 抖阴旅行射-Boulder and who now works at Cochlear Americas in Centennial, Colorado. 鈥淏ut music is a different animal and hasn鈥檛 always been part of the hearing aid design process.鈥�
A frequent complaint among people who use hearing aids is that music can sound distorted, said Croghan, and it鈥檚 common for people to remove their hearing aids to listen to music.
Modern hearing aids use processing called 鈥渨ide dynamic range compression,鈥� which leaves loud sounds untouched but amplifies softer sounds. This kind of processing is useful for helping people with hearing loss follow a conversation, but it can distort music, which often covers a wider range of volumes than speech.
Adding to the distortion is the fact that recorded music commonly undergoes its own processing, known as 鈥渃ompression limiting,鈥� which squeezes louder and softer sounds together into a narrower range, increasing the perceived volume. Too much compression limiting can affect the quality of music even for people with normal hearing, Croghan said, but it compounds the problem for hearing aid users.
鈥淭he recorded music is processed through multiple layers by the time the person with hearing loss actually hears it,鈥� Croghan said.
The research team鈥攚hich also included Professor Kathryn Arehart and Scholar in Residence James Kates, both in 抖阴旅行射-Boulder鈥檚 Department of Speech, Language and Hearing Sciences鈥攁sked 18 experienced hearing aid users to listen to classical and rock music samples that ranged from being unprocessed to highly processed. The participants also used simulated hearing aids set at a variety of processing levels.
Regardless of which music sample the participants listened to, they generally preferred using the hearing aids with the simplest additional processing鈥攅ssentially devices that just boost the volume. The participants also tended to prefer less processed music to more processed music. However, the level of processing of the music itself wasn鈥檛 as important as the type of hearing aid used for listener enjoyment.
鈥淲hat鈥檚 interesting about this is that more is not necessarily better,鈥� Arehart said. 鈥淚f I am in a noisy restaurant and I want to hear the people at my table, then more processing may be better in order to suppress the background noise. But when listening to music, more processing may actually do more harm than good.鈥�
Despite general agreement among study participants that less processing in the hearing aid was better for listening to music, individual preferences varied from person to person.
鈥淲hen it comes to hearing, like a lot of things, the average result does not fit everyone,鈥� Croghan said.
The study was funded by a grant from hearing aid manufacturer GN ReSound.
