Human's ability to perceive melodic pitch isn't unique

Washington: Seems like we are not alone in how we perceive a melodic pitch as marmosets have showcased the same talent.

The specialized human ability to perceive the sound quality known as 'pitch' can no longer be listed as unique to humans. Researchers at Johns Hopkins report new behavioral evidence that marmosets, ancient monkeys, appear to use auditory cues similar to humans to distinguish between low and high notes.

The discovery infers that aspects of pitch perception may have evolved more than 40 million years ago to enable vocal communication and songlike vocalizations.

Xiaoqin Wang said, "Pitch perception is essential to our ability to communicate and make music but until now, we didn't think any animal species, including monkeys, perceived it the way we do. Now we know that marmosets, and likely other primate ancestors, do."

Wang says that other animal species have been reported to show pitch perception, but none have shown the three specialized features of human pitch perception. First, people are better at distinguishing pitch differences at low frequencies than high. Second, humans are able to pick up on subtle changes in the spread between pitches at low frequencies or hertz, so they notice if a series of tones is increasing by 100 hertz each time and then introduces a tone only 90 hertz higher. And third, at high frequencies, peoples' ability to perceive pitch differences among tones played simultaneously is related to how sensitive they are to the rhythm, or timed fluctuations, of sound waves.

Through a series of hearing tests, with waterspout licks as a readout, Wang's team, led by graduate student Xindong Song, determined that marmosets share all three features with humans, suggesting that human components of pitch perception evolved much earlier than previously thought.

The research is published online in the journal Proceedings of the National Academy of Sciences.