Marmosets Can Perceive Melodic Pitch, Just Like Humans

Humans are not the only ones who can perceive the quality of sound, otherwise known as "pitch."

Now, researchers at Johns Hopkins have found that marmosets appear to use auditory cues similar to humans that help distinguish between low and high notes, as well.

"Pitch perception is essential to our ability to communicate and make music," said Xiaoqin Wang, Ph.D., a professor of biomedical engineering at the Johns Hopkins University School of Medicine, in a news release, "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."

Researchers noted similar brain activity between humans and marmosets about 10 years ago, when the nerve cells in the primary auditory cortex of the marmoset brain fired only after being exposed to sounds with pitch and not just nose. Human brains show similar activity in the same region, according to Wang. However, at this time, he was unable to show behavioral evidence that the marmosets could perceive and respond to differences in pitch the same way that humans do.

Over the next 10 years, the researchers developed behavioral tests and electrophysiological devices that monitored subtle changes in the monkeys' neural activity. While they found that the animal species reported pitch perception, they needed to determine if they carried three specialized features unique to human pitch perception; the human ability to better distinguish low frequency pitches over high ones, the human ability to pick up on subtle changes in the spread between pitches at low frequencies or hertz, and the human ability, when at high frequencies, to perceive pitch differences among tones played simultaneously--revealing how sensitive the human ear is to time fluctuations, sound waves and rhythm.

The study showed through a series of hearing tests that marmosets share all three features, as well. The findings suggest that human components relating to pitch perception evolved much earlier than once thought.

"In addition to the evolutionary implications of this discovery, I'm looking forward to what we will be able to learn about human pitch perception now that we have a primate relative we can study behaviorally and physiologically," says Wang. "Now we can explore questions about what goes wrong in people who are tone deaf and whether perfect pitch is an inherited or learned trait."

The study is published in the Proceedings of the National Academy of Sciences (PNAS).

Related Articles

'Inattentional Deafness' Cuts Off Sound From Your Environment

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).