by prettiestPony » 28 Jun 2012 21:17
Googling the phrase in quotes only gives about 1100 results, many of which (from a cursory glance) seem to be just showing up because the terms were listed next to each other, not because it was part of the same term. So, it's hardly common usage. My first guess, however, would be, yeah, digital clipping: the wave amplitude gets so high that it "overflows" and gets clipped. That seems to be confirmed by the comment Artimeus found.