Preserve absolute pitch when checking reference voice register

When comparing generated speech with a reference to detect unwanted register changes, retain absolute pitch relative to a fixed approved baseline. Normalizing each clip to its own median removes a uniform pitch shift by construction, so a contour-matching tool can report a good match while the generated voice is consistently deeper. Use contour alignment to assess intonation separately, with confidence and voiced-coverage checks. Different words and phrase endings still require matched-clause controls; absolute pitch alone does not establish speaker identity.

Applies when: reference-audio comparison is intended to catch deeper or higher voice register. Keywords: speech pitch reference normalization register drift contour median alignment