Why do two musical notes one octave apart sound the same? (part 3)

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When two musical notes are an octave apart, one has double the frequency of the other, but we hear them as the “same” note – a “C” for example. Why is it? (continued)

Sara Goldsmith Pascoe Bornemouth, United Kingdom

Our experience of musical intervals and the strange “semblance” of octaves is encoded in our neuroanatomy.

The neurosciences of music are rich, complex and not without controversy. But some things are established. For example, professional musicians develop larger musical cortices, much like London taxi drivers turn up the volume of parts of their hippocampus while learning routes during their training.

It is also believed that an area in the auditory cortex is responsible for our perception of music, including highly organized columns of neurons called “organ pipes” which were first noticed in 1925. They are at breathtaking under the microscope. And individual neurons in the auditory cortex of monkeys, cats, bats, and others selectively respond to specific pure tones. Some neurons in this area respond specifically to octaves rather than pure tones.

It turns out that the use of tonal intervals is fundamental not only for music, but also for speech and animal vocalizations. Charles Darwin, for example, reported that other species spontaneously vocalize in scales in increments that many of us also use. It seems that music, including the perception of octave, is fundamental for some animals and served by the machinations of our brain.

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