That's a good point, and we are on it: http://journal.frontiersin.org/article/10.3389/fnins.2016.00... We are working on a follow up in this direction with more cultures. (N.J)

Nice! Looking forward to seeing where this leads :)

Some of our preliminary research about speech rhythm did get to the Current Biology paper. Figure 6 in the paper uses the method to study prosody of 5 sentences in English. (N.J)

1:1:1 is an isochronous (equal) rhythm. Most of the rhythms in the paper are played repeatedly, so the last note has the same duration.