This article is fascinating:
http://doi.org/10.1007/s10988-014-9155-7The abstract is worth a read, though the article itself is very technical. But I like seeing a technical analysis like that of something other than Human Language.
Of course I have to admit my favorite part is the following sentence

a1. Eagle shrieks
(i) hhhk
(ii) hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhWhhhh WWhHWhhWWhWhhWhWhWWwhWWWwWhhKhKKKWKWKKKh hKWWKKKKKKKKKKKKKKKKKKKKKKK
But (fortunately? unfortunately?) those are just abbreviations:
Abbreviations
boom = b, krak = k, krak-oo = K, hok = h, hok-oo = H, wak = w, wak-oo = W