By Carolyn Heneghan
Picture a world where the deaf and hard of hearing can enjoy music just as much as an uninhibited listener. While scientists have made progress toward that goal by enabling the ability to hear and understand speech in quiet environments, hearing music is not yet perfected. But researchers at the University of Washington in Seattle have developed an algorithm for cochlear implants wherein music sounds pleasing, rather than like a jumbled bunch of sounds.
Music in the Cochlear Implant
According to the University of Washington website:
A cochlear implant is a small, electronic device that lets a person who is profoundly deaf or hard of hearing perceive sound. One piece is placed on the skin behind a person’s ear, while another portion is surgically inserted under the skin. The implant works by directly stimulating the auditory nerve, bypassing damaged portions of the ear. The implant’s signals are sent to the brain, which recognizes the signals as sounds.
The standard implants use a special algorithm to categorize sounds into high, middle and low frequencies. The problem with these standard implants is that the algorithm is too stiff to properly hear music. Regular sounds such as speech are audible, but music’s shifting pitches and the instrumental timbres are too complex to hear. Furthermore, implant users can only hear one voice at a time, as background noise and multiple voices produce a cacophony of sound—another reason why the combinative instrumentation in most music would be difficult to hear.
“If you sing ‘Happy Birthday to You’ to someone who has a cochlear implant, they’ll have no difficulty understanding what you’re saying, but if you play a version that is devoid of lyrics or rhythm, they can’t tell the difference between that and ‘Twinkle, Twinkle Little Star,’” explains Rubinstein, a professor of otolaryngology and bioengineering at the Virginia Merrill Bloedel Hearing Research Center.
He continues, “The other thing they can’t hear is timbre. So we have several instruments play the same five-note sequence and ask them to say what’s the guitar or what’s the piano. Someone who has normal hearing will do this test virtually perfectly, but someone who has a cochlear implant will score very poorly.”
The Researchers’ Laudable, Audible Results
The new algorithm developed by the university changes all of that. Whilst wearing cochlear implants embedded with this music-decoding algorithm, the average implant user scored a 45% on the timbre test, and the test subject who performed the best in the experiment reached nearly 90%. In terms of pitch, the new algorithm could expand most of the test subjects’ recognition of a single octave to three octaves. This advancement coupled with the ability to interpret rhythm and words through natural speech comprehension are pieces of the puzzle to eventually fully hear and understand music. Read More →