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Your co-worker’s annoying humming may be more virtuosic than you think. People without musical training naturally improvise melodies that have hallmarks of tunes composed by professionals, a new study shows. It seems that most individuals follow the arcane rules of music composition, even those who are unaware those rules exist.

“It’s cool,” says Samuel Mehr, an expert on the psychology of music at Yale University who was not involved in the work. The study offers an “elegant” way to test people’s musical abilities. “It definitely feels like a real phenomenon, not some kind of contrived thing that a bunch of psychologists made up in the lab.”

The study concerns a musical concept known as tonality—the fact that songs almost always use a subset of all the pitches a voice or instrument can produce. For example, a standard piano has 88 keys, but the typical piano piece tickles just a fraction of them. If you play a piano’s keys one by one from left to right, the notes will climb steadily in pitch until the 13th note sounds just the same as the first note, only higher. This defines an octave.

Melodies usually stick to the same four to seven pitches in each octave that are called the scale notes. That is why, in the classic movie musical The Sound of Music, the von Trapp children learn just the seven notes “Do Re Me Fa So La Ti Do” of the most common type of scale in Western music. Out-of-scale pitches can sound jarring, but musicians sprinkle such “accidentals” into tunes to add elements of tension, color, and surprise (such as the middle syllable of “Maria” in this song from West Side Story). One note in the scale, the tonic, acts as the central pitch, which often starts and ends a song.

Tonality appears in music across diverse genres and cultures, though the scales differ greatly between, say, Indian classical and American folk. In part because of this ubiquity, some researchers suspect tonality might be an evolved human trait, which helps our brains perceive, remember, and create music. But it remains unclear how—or how well—average people understand tonal rules.

In studies investigating this question, participants typically evaluate or choose a final note for an existing melody—like filling in a sentence’s missing word on a language exam. Most folks ace the tonality test, but they may just be completing a familiar sequence of pitches heard repeatedly during the experiment or everyday life.

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Weiss et al., Scientific Reports 2022

For a better measure of tonal proclivities, Michael Weiss and Isabelle Peretz, psychologists at the University of Montreal, developed a test akin to writing grammatically correct sentences from scratch (listen above). In soundproof booths equipped with headphones and microphones, participants improvised melodies, crooning only “da,” in response to prompts such as instructions to sing a lullaby, a dance, a sad song, etc.

The researchers weren’t sure subjects would want to perform the task. “It’s kind of an intimidating thing,” Weiss says. But, “Once we got people singing, they were quite happy to continue.” The jams typically ran 20 seconds with 30 notes, and some had to be cut short, Weiss recalls. “They would just continue improvising for minutes without some intervention.” One participant enjoyed the experiment so much, she enrolled in singing lessons.

The researchers captured 924 recordings from 33 residents of Quebec, including 18 participants with congenital amusia—commonly known as tone deafness. In the most prevalent form of this condition, which is estimated to affect 1.5% to 4% of the population, individuals struggle to perceive and produce pitch. But typical and amusic brains show similar electrical responses to out-of-scale notes. And, through her decades of research, Peretz has observed amusic individuals sing melodies that sounded tonal to her, even as they failed to distinguish pitches themselves.

In the current study, Peretz and Weiss created an algorithm with which a computer matched the improvs to the closest scale from Western music. For seven of the 18 amusics and 13 of the 15 controls, the participants’ songs kept to these scales better than sequences of random notes did. About the same number of participants ended their melodies on tonics more often than chance. Collectively, the musically neurotypical group fared better, but a few amusics outperformed controls, the team concluded last month in Scientific Reports. These amusic individuals “are singing in a way that adheres to a tonal system, even if they’re having difficulty perceiving that,” Weiss says. One amusic and several controls scored higher than a professional baritone with 11 years of formal training. 

The study supports psychologists’ current understanding of how brains make music, according to Kathleen Corrigall, a cognitive scientist at MacEwan University. People, including individuals with amusia, develop implicit knowledge of music rules, and are often unaware that they hold this knowledge. “The findings didn’t surprise me,” she says, but the study’s use of sung improvisation “struck me as a pretty creative, novel way to measure” implicit knowledge about tonality and other music rules.

Psychologist Erin Hannon, who leads a music cognition laboratory at the University of Nevada, Las Vegas, also praised the improv approach. “I’m a big fan of any method that can be used with a whole bunch of different kinds of people, and you don’t need people with particular skills in order to do it,” Hannon says. The easy-to-run experiment and new algorithm could be used to compare tonality across different age groups and cultures, or even among different creatures. Such a tool could help scientists uncover the aspects of musicmaking shared by all humans and unique to our species. So, go ahead, sing us a song whether you’re the piano man or the plumber.

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