The first step in making cat music is "to evaluate music in the context of the animal's sensory system," researchers said.
"We are not actually replicating cat sounds. We are trying to create music with a pitch and tempo that appeals to cats," said lead author Charles Snowdon, professor of psychology at the University of Wisconsin-Madison.
Cats, for example, vocalise one octave higher than people, "so it's vital to get the pitch right. Then we tried to create music that would have a tempo that was appealing to cats," researchers said.
In the tests, Snowdon and Megan Savage, former UW-Madison undergraduate student (now a PhD student at Binghamton University) played four sound samples to 47 cats: two from classical music, and two "cat songs" created by University of Maryland composer David Teie.
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The music began after a period of silence, and the cat's behaviour was noted. Purring, walking towards the speaker and rubbing against it were adjudged positive response, while hissing, arching the back and erecting the fur were negative.
The cats were significantly more positive towards cat music than classical music. They began the positive response after an average of 110 seconds, compared to 171 seconds for the human music.
The cats showed almost the same number of aversive responses to each type of music.
The study follows a 2009 report by Snowdon and Teie, which showed that a monkey called the cotton-top tamarin responded emotionally to music composed specifically for them.
That work led Snowdon and Teie to believe that "the same features that are effective in inducing and communicating emotional states in human music might also apply to other species." These features include pitch, tempo and timbre.
The study was published in the journal Applied Animal Behaviour Science.