The response preserves the native sample rate when none is requested. The HNR helper assumed 24 kHz, halving the perceived pitch of dots.tts-soar output and using the wrong autocorrelation window. Let PCM tests declare the native rate, honor requested resampling rates first, and retain the quality thresholds. Cover the failure with a 120 Hz synthetic voice and rate-selection tests.
Signed-off-by: tzhouam <tzhouam@connect.ust.hk>