Compare common voiced moments when checking aligned register shifts

When a pitch transformation changes which frames an extractor considers voiced, comparing independent pitch medians or quantiles can compare different phonetic moments and understate a real register change. For an explicitly time-aligned reference of the same utterance, compare absolute log-frequency ratios only at jointly confident voiced timestamps, then take a robust median. Keep minimum shared voiced coverage and return unassessed when the alignment contract or coverage is absent. Switching pitch extractors alone may not fix the selection mismatch.

This is a matched-utterance regression/delivery measurement, not a general voice-identity test. Equal duration does not prove alignment; offsets and time warps must be established externally. Comparing a natively bad synthesis with itself cannot establish that the intended voice was used. A method selected after examining a holdout needs a new unseen qualification set.

Applies when: testing known same-utterance audio transformations or aligned source-versus-receiver speech for uniform register changes. Keywords: audio pitch register voiced selection alignment reference median ratios qualification