We did the test again with Fidelity 120. I did better on the melody test this time, scoring about 20 percent. That was closer to the mean score, which, Rubinstein told me, was 25 percent.
But John Redden had done far better. Redden gave me his score on the melody test: 100 percent. For a cochlear-implant user, that was an extraordinary score. Having a professionally trained brain for music probably helped. Richard Reed, a musician who had lost his hearing at 37 and gotten an implant at 46, had scored 86 percent. Only a handful of the subjects had gotten scores in that range.
Rubinstein says that people like Redden and Reed are proof of what’s possible. He told me, “I don’t want to lead people to unrealistic expectations of the ability to hear music with a cochlear implant, but in fact, the results are better than we expect.” There were, of course, the high scorers, but even many of the low scorers on the melody test had still done well on the pitch-perception test, as I had.
The scores suggested that the nascent capacity to perceive pitch was there, waiting to be exploited with better software and better training. For example, Rubinstein’s lab has been experimenting with an algorithm using a phenomenon called stochastic resonance to improve music perception.
So there was a good reason for the melody test to be hard, I realized. It was not an impossible test for implant users, but merely a very difficult test. It was a simple, easy to use, and reliable test that let researchers measure the performance of new algorithms objectively. (A paper giving data on a larger group of subjects and demonstrating test-retest reliability is currently in review, Rubinstein says.)
The test also lets subjects measure progress over time. If in 10 years scores have doubled, that will mean that implant users really are hearing the basic elements of music better.
The test would also make it easier for researchers to analyze the performance of “superlisteners” like John Redden so that, ultimately, they can develop new software to let other deaf people hear music better.
Michael Chorost covers implanted technologies for Technology Review. His book, Rebuilt: How Becoming Part Computer Made Me More Human, came out in 2005.