As my friends are learning about my current obsession with tuning systems, they’re starting to ask interesting questions I don’t know the answers to.
For example, Michael Fourman asked me: if harmonies coming from simple fractions are so natural, do any bird or whale songs feature such harmonies?
It turns out an Australian bird called the pied butcherbird has long been a favorite of many composers! Jean-Michel Maujean figured out the frequency ratios that appear in the songs of this bird. He found the 4 most common ratios are close to
He notes that
• 0.607 is close to going down a major sixth (3/5),
• 0.745 is close to going down a major third (3/4),
• 0.815 is kinda close to going down a major third (4/5),
• 1.34 is close to going up a perfect fourth (4/3).
His work looks good—but he shouldn’t have bothered comparing the ratios to 12-tone or 18-tone equal temperament. Equal temperament is a system developed for keyboard instruments in the late 1700s. It would be amazing if the birds used this!
Maujean also has a nice review of the literature on harmonies in bird songs, so I should dig into it:
• Jean-Michel Maujean, Analysing Intonation of the Pied Butcherbird, honors thesis, Edith Cowan University.
You can hear a pied butcherbird here:
But I get the feeling that most birds don’t sing with frequency ratios that are simple fractions. What’s up with these other birds?