# Source-level gravel (eab00f26)

Roughness ladder r10/r50/r85 on medium-clear-jolly (barely-textured /
weathered / genuine gravel), plus before/after A-B for
big-gravelly-gruff (the owner's 'light on gravelly' complaint) and a
clean-voice regression reference (jolly, roughness 0.097).
Fry = per-cycle period jitter + subharmonic alternation + shimmer,
at the glottal source, before the formant filters.