That question only seems to appear in the press release - it may be a reference to an earlier study, but press releases don't tend to cite sources. The paper in question is theoretical, although it gives an example with the intensity of various human and animal sounds. (I have access through my university)

One thing not mentioned in the paper is also music. Each octave increases exponentially (each is twice the frequency of the previous). However our ears perceive the difference between notes as linear (it is actually linear if you take the log of the frequency). One theory is due to the shape of the inner ear, where the individual hairs that hear sounds each octave apart are spaced lineally.