Sept. 29, 2005 — Scientists have taught dolphins to combine both rhythm and vocalizations to produce music, which has resulted in an extremely high-pitched, short version of the "Batman" theme song.

The findings, outlined in two studies, represent the first time that nonhuman mammals have demonstrated that they can recognize rhythms and reproduce them vocally.

"Humans are sensitive to rhythms embedded in sequences of sounds, but we typically consider this skill to be part of processing for language and music, cognitive domains that we consider to be uniquely human," said Heidi Harley, lead author of both studies. "Clearly, aspects of those domains are available to other species."

The studies will be presented at the joint meeting of the Acoustical Society of America and NOISE-CON 2005, which runs from Oct. 17-21 in Minneapolis.

Harley, who is associate professor of social sciences at the New College of Florida in Sarasota, told Discovery News that both studies tested dolphins at The Living Seas exhibit at the Disney World Resort's Epcot Center in Lake Buena Vista, Fla.

The researchers first had an adult male bottlenose dolphin position itself in front of an underwater sound projector, called a hydrophone, that produced six different 14-kHz, four-second rhythms. The dolphin was rewarded for performing a certain behavior to each rhythm.

For example, when Rhythm 1 played, it waved its pectoral fin and when Rhythm 2 played, it tossed a ball.

The various rhythms were played at different frequencies and tempos to ensure the dolphin was recognizing rhythms instead of just frequencies or sound durations.

Another adult male next was trained to produce similar rhythms using a pneumatic switch, which essentially is a small, air-filled ball that is connected to a computer that then generated sounds whenever the dolphin depressed the switch.

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