Friday, December 14, 2012

Hear, Hear! A Call for Music

I got my information from a TED Talk by Charles Limb and from an MIT Technology Review article by Michael Chorost.

Science and technology have made amazing progress in terms of aiding the hearing impaired. In the 16- and 1700s, the best science had to offer were hearing trumpets that funneled sound to the ear from a larger opening at the opposite end of the device. Later on, in the 1800s, attempts were made to make hearing aids more subtle, though perhaps a bit ridiculous, like ear-shaped devices with small funnels that one would wear like earmuffs. Todays cochlear implants are a vast improvement over, say, walking around with two sets of ears. Unlike hearing aids, which amplify sounds, cochlear implants directly stimulate the auditory nerve which sends sound signals to the brain, bypassing any damaged portions of the ear. Their primary function is to help people hear spoken language. This, of course, is great and tremendously useful, but CIs still have many challenges to face. One of these challenges is allowing its users to hear music.

Today's cochlear technology relies on the semantic-specific nature of spoken language. What matters is that a message is communicated correctly, not that the message sounds nice when spoken. In more visual terms, the letter “t” can be written many different ways depending on a person's handwriting or a font used on the computer. The visual aspect of the “t” is unimportant. All that is needed is the recognition that it is the letter “t” and not any other symbol. This is the way spoken language works, and so that is what cochlear technology uses to aid in hearing and communication. Music, however, works almost oppositely. What is music if not something that sounds nice?

This graph shows the difference between the sound levels and frequencies needed to hear spoken language and those needed to hear music.
CIs only transmit what is needed to hear language.

One of the main problems with CIs allowing people to hear music is a matter of pitch perception. Most people with standard hearing can differentiate between pitches that are 1.1 semitones, the smallest pitch interval in Western music, apart. CI patients' pitch perception can be off as much as two octaves. This is a considerable difference. Another problem arises with the inability of most cochlear implant users to discern between various instruments. With a device that focuses on the fundamentals of communication rather than sound quality, things like warmth and timbre are not transmitted.

Researchers at the University of Washington and the University of Iowa are working on breaking down the components of music to help CI users hear it. Their computerized test called the Clinical Assessment of Music Perception (CAMP) divides the very complicated unit known as music into three parts: pitch, timbre, and melody. The perceptibility of each component can be tested by CI patients, and these tests have shown the presence of the ability to perceive pitch. The tests can also show progress over time, perhaps with advances in technology. For example, if test scores improve, there is a good possibility that music perception is actually increasing amongst CI patients.

Beethoven managed to compose beautiful music in spite of his profound deafness. If he accomplished so much with a simple hearing trumpet, imagine what can be done with today's ever-evolving technology. Both music and human beings are extremely complex, but beautiful in their complexity, so to get them to work together in (are you ready for it?) harmony will be an amazing accomplishment. The universal ability to hear music may be a long way off, or that technology might be available within the next few years. Who knows? Either way, I'm excited. Music is just one of those things that can't be explained. It has to be experienced firsthand, and everyone should have to opportunity to feel it.

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