Human-Style Sound Modulation For the Birds, Researcher Finds

Birds sing like humans, a scientist said Wednesday, countering a widely held theory that birds produce notes on a more primitive scale.

In a report in the British science journal Nature, biology professor Stephen Nowicki of Rockefeller University said birds modulate sound gushing from their windpipes into distinctive notes much the way humans modulate sound into distinctive consonants and vowels by shaping their mouths and tongues.

Nowicki said be believes birds modulate sound by lengthening and shortening their trachea like a trombone, and widening and narrowing the opening of the tracheal passage like a concertina.

“Their beaks and tongues are pretty stiff,” he said, “although they may play some role in modulation also.”

Nowicki said only a handful of creatures, such as frogs, are known to modulate sounds the way humans do.

“Birds and humans are much alike in that the youngsters of both have to learn to communicate with sound by listening to their elders,” Nowicki said. “Now I find the way they produce sound is more similar (to humans) than previously thought.”

Nowicki placed dozens of song sparrows, a small bird common in the Northeast, into aquariums filled with 80% helium and 20% oxygen. Sound waves increase in velocity when traveling through helium, allowing Nowicki to measure the birds’ songs with monitoring equipment that indicated they could modulate sound.

He said the ability to modulate probably holds true for all birds, not just song sparrows.