Behind the rousing song of an all-male choir lies an evolutionary force that is better known for shaping the sex lives of hopeful frogs and crickets, research suggests.
Recordings of an elite boys’ choir once directed by Johann Sebastian Bach in Leipzig, Germany, reveal that the more physically mature boys in the group boosted their vocals with an appealing ring when girls were in the audience.
The effect, seen only among the older bass singers, aged 16 to 19, is thought to be the choral equivalent of behaviour more often observed in frogs and crickets, which alter their individual calls to stand out from the crowd during mate-enticing choruses.
“The boys’ singing sounds more brilliant and has a more attractive, ringing quality when girls are in the audience, but it is subtle,” said Peter Keller, a professor of neuroscience who led the work at the centre for music in the brain at Aarhus University in Denmark.
Keller and his colleagues teamed up with the renowned St Thomas choir in Leipzig after a student and former member of the choir mentioned that the boys’ singing seemed to change in a barely perceptible manner when female audience members were present.
Acoustic analysis of the boys singing a chorale and a fugue composed by Bach found that in the presence of girls aged 15 to 16, the boys with the deepest voices boosted their vocal brilliance and carrying power by diverting more energy into a frequency band around 3,000Hz known as the singer’s formant.
But it was unclear whether people, as opposed to sensitive acoustic devices, could detect the subtle shift in vocals, and if they could, whether the resulting sound was more or less appealing because of the enhanced singer’s formant.
To find out, the researchers ran two online studies in which 2,247 male and female volunteers listened to audio clips of the boys singing with and without girls in the audience. While both male and female participants noticed a difference between the two performances, only female volunteers preferred the singing with the boosted singer’s formant. “It’s really subtle and probably something that’s subconscious,” Keller said. Details are published in the journal Biology Letters.
“It’s not that every person who listens to this will detect it or prefer it – it’s a statistical phenomenon that happens at a larger scale, at the population level,” Keller added.
For the recordings, the boys performed once before an all-male audience and a second time when a group of teenage girls joined the front row on the pretence of being on a school trip. In post-concert interviews, the boys felt they sang better in front of the girls but none admitted to trying to attract their attention.
Whether individual bass singers stood out in the performance is unknown. One possibility is that the boost from the singers with the deepest voices drew attention to the bass section more generally. Besides the four basses, the choir included four tenors aged 16 to 18, four altos aged 12 to 16 and four sopranos aged 12 to 13.
According to the scientists, the findings suggest choir singing is a special form of social communication where cooperation and competitiveness, the latter potentially sexually motivated, can exist alongside one another. “You have a group of people working together,” said Keller, “but at the same time individually having this parallel channel of communication, sending out the competitive signal saying: pick me!”
