Maybe http://trac.webkit.org/changeset/158220 ?
> diff-wav.py /Volumes/Users/jer/Downloads/oscillator-sawtooth-expected.wav /Volumes/Users/jer/Downloads/oscillator-sawtooth-actual.wav
Total differing samples: 1
Percentage of differing samples: 0.001%
Cumulative sample difference: 1
Average sample difference: 1.000000
Looks like the first sample is ever so slightly different. Unlikely to be related to the checkin in question.