Monday, November 24, 2008

Human neurons are extraordinarily sensitive to changes in pitch

Reference: Fritz, S. (2008). Why dogs don’t enjoy music: Human neurons are extraordinarily sensitive to changes in pitch. Scientific American: Mind, 19(5), 15.

Review: This particular article is succinct and full of information. It discusses human neurons and how extraordinarily sensitive they are to changes in pitch. It then compares humans to other mammals. Researchers have, and continue to find it strange that humans can distinguish between the musical tones in a scale. Izhak Fried of U.C.L.A. and his colleagues were able to study the auditory cortex in great detail when working with epileptic patients who had electrodes implanted in their brain to pinpoint the source of their seizures. “The study revealed that groups of exquisitely sensitive neurons exist along the auditory nerve on its way from the ear to the auditory cortex. In these neurons natural sounds, such as the human voice, elicit a completely different and far more complex set of responses than do artificial noises such as pure tones.” This means that humans can detect frequencies easier than other mammals, in fact, humans can detect frequencies as fine as one twelfth of an octave. What can we do with this information? The researchers main question is why is this the case? As far as we know, bats are the only mammal with better ability to hear changes in pitch than humans. Dogs and other mammals are not nearly as sensitive suggesting that fine discrimination of sounds is not necessary for survival. Researchers speculate that humans use their “fine hearing to facilitate working memory and learning capabilities, but more research is needed to explore this puzzle.” 


Reflection: I found this article really neat, merely for content. I find it really strange that humans can distinguish between sounds so easily. Thinking of a previous blog I wrote on the article Monkeys Hear Voices, I found it strange to learn that macaques can resolve only half an octave. I would have thought it would be more, since macaques can distinguish human voices. It will be fascinating to read more on this research as it continues to develop. I wonder if there are other reasons why humans can distinguish between different pitches. Perhaps it is because we are so advanced in our use of vocalizations? 

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