We all know it: we are not equal when it comes to singing. Where the voices of Maria Callas or Freddie Mercury trigger immediate emotion and attract crowds, it is gagged at the foot of an oak tree that Assurancetourix ends the evening. A story of donation, of course. But also work, the singers will assure you. “That’s what they say,” concedes Iris Adam, lecturer in biology at the University of Southern Denmark. But we have no scientific proof, in any species, that vocal performance requires regular muscle training. » The researcher should express herself here in the past tense. Because, in an article published on December 12 in the journal Nature Communications, she and her Danish, Swedish, Dutch and American collaborators have just provided proof that, for zebra finches, singing well requires practice every day.
Why zebra finches? “Firstly because no singer will let you take tissue samples from their larynx,” explains the researcher. To be completely transparent, the 79 males studied at the University of Southern Denmark also did not agree. But let’s say that their participation has advanced science… Another interest: the male zebra finch emits a particularly modulated song which has made it a model animal in this area. Finally, these birds never stop singing. To impress their future partners, to defend their territory, to maintain social ties. Or for nothing, at least apparently. Even alone, they don’t just breathe and scream: they sing.
To study the role of training, scientists took advantage of the fact that birds have two parallel neuromuscular circuits, one per hemisphere. By cutting one of the two circuits, they found that in two days the vocal muscles lost 50% of their volume and tone. But what would happen if they were deprived of just the ability to sing? To do this, simply keep them in the dark. They call, but no longer sing. Again, the scientists found a loss of half their muscular efficiency: still 50%, but this time within seven days. A rapid fall that surprised the research team.
Females choose good singers
It remained to be seen whether this drop in performance would have consequences. After all, Françoise Hardy or Alain Souchon, adored by their fans, have never stood out for their volume. The researchers therefore asked thirteen females to “choose” between two songs broadcast in playback. On one side, the bird before its week in the dark; on the other, the same, but later. And, in 75% of cases, these ladies opted for the former. “A fascinating result obtained after particularly rigorous experiments,” greets Nicolas Mathevon, professor of bioacoustics at the University of Saint-Etienne.
