Humans are remarkably talented musicians. We can recognize a tune despite changes like being slowed down or sped up or even if all of the notes are shifted to a higher or lower pitch. Though these may seem like trivial feats, most other animals can’t manage them. Experiments have shown that six-month old human babies can already distinguish musical pitch and recognize shifted melodies. These exceptional abilities suggest that humans might have some innate capacity to perceive and understand music, something like our hypothetical language faculty. Given that we’ve been able to sing for much longer than we’ve had musical instruments, it seems reasonable that any music capacity we evolved would be more attuned to vocal than instrumental music.
To test this idea, Michael Weiss, Sandra Trehub, and Glenn Schallenberg investigated whether people remember vocal or instrumental melodies better. They made a collection of 32 folk tunes recorded in four different ways: a singer repeating the syllable “la” and three instrumental versions played on a piano, a banjo, or a marimba. Participants in the experiment listened to four melodies of each type, for a total of 16 melodies; to make sure that the results weren’t affected by how memorable individual songs were, the songs were shuffled so groups of participants heard different songs as vocal or instrumental. After a short break, they listened to all 32 melodies (16 of which they hadn’t heard) and had to rate how familiar they sounded. The difference between the familiarity of the new songs and the old ones told the researchers how well people were remembering them.
The trio found that people remembered the tunes they had heard sung significantly better than those played on an instrument. This was true even after the team used a computer program to even out differences between the versions, so it wasn’t a consequence of the vocalist being more expressive or other differences in performance. It also wasn’t because people are more used to hearing voices — the instrumental versions were all equally memorable even though people said the piano sound was more familiar. It seems that something about the timbre and quality of the human voice simply makes it more memorable.
The scientists don’t really know why that’s the case, but they speculated that it might be because the biological significance of the voice — the fact that we recognize it as the sound of another human — makes us respond more attentively and process it more than we do an instrument. Regardless of the exact hows and whys of the matter, it’s clear that humans remember vocal music better than other kinds. In addition to warning researchers to distinguish between vocal and instrumental music in future studies, these results also provide one more piece of evidence that a prediliction for music may have been shaped by evolution, an important part of being human.