‘I know this song!’ Evolutionary keys of musical perception

How do we perceive music and sounds? This question is the basis of research from the Language and Comparative Cognition Group (LCC) of the UPF Center for Brain and Cognition (CBC) recently published in the journal animal cognition.

Humans share characteristics that so far seem unique in the animal kingdom: language and music. “Our group is dedicated to understanding how these skills evolved in humans and to what extent some of their components are shared with other species,” says Juan Manuel Toro, director of the LCC and one of the authors of the study, with Paola Crespo Bojorque and Alexandre Celma Miralles.

When we hear a song we already know, we can identify it even though it’s not an exact version of the original. If it sounds higher or lower, faster or slower, or if the instruments are different from the known version, humans can identify it even if there are these superficial changes in the melody. The LLC study explores the extent to which this skill is based on skills that are also present in other animals, i.e. not unique to humans.

Therefore, they studied 40 lab rats (Rattus norvegicus, commonly known as Long-Evans rats), trained to identify a melody, in this case using the second half of the song “Happy Birthday”. “It is a thirteen-tone melody that includes the entire pitch range of Western major scales,” they explain in the article.

The experiment began with a familiarization phase followed by three test sessions. Twenty familiarization sessions were held, each session lasting 10 minutes per day. At each session, rats were placed individually in a response box and presented with 40 repetitions of the familiarization tune while receiving a sucrose pill as food.

The results suggest that the ability to recognize patterns of pitch and tempo changes present in humans may emerge from pre-existing abilities in other species.

After the familiarization phase, three sessions took place in which modified versions of the song were used. Responses to the following physical changes in melody were analyzed:

  • Fundamental Frequency (Pitch): The song was played one-eighth above or below the original.
  • Speed ​​(tempo)
  • Stamp. The original song was played on the piano and the variation on the violin.

“Our results show that the rats recognized the song even when there were changes in frequency and tempo,” Toro explains, “but when we changed the timbre, they were no longer able to recognize the song. suggest that the ability to recognize patterns in pitch and tempo changes present in humans may emerge from pre-existing abilities in other species.”

Some species of mammals and birds can perceive changes in fundamental frequency (rhesus monkeys -Macaca mulatta), tempo (California sea lion -Zalophus californianus- or cockatoo -Cacatua galerita eleonora) and timbre (chimpanzees -Pa troglodytes). However, Toro explains that humans process music by perceiving musical structures relatively rather than absolutely; that is, independent of surface changes along characteristics such as pitch, tempo, and timbre. It is therefore important to understand to what extent this capacity relies on sensitivities already present in other species.

The research was carried out with the support of the Barcelona Biomedical Research Park (PRBB), the BIAL Foundation and the Catalan government.

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Materials provided by Pompeu Fabra University – Barcelona. Note: Content may be edited for style and length.