Per-synthesis options that may override instance defaults.
Optional
Pitch multiplier — 1.0 = normal pitch.
1.0
Speech rate multiplier — 1.0 = normal speed.
Voice ID / name recognised by the backend (e.g. "en-US-Neural2-F").
"en-US-Neural2-F"
Volume in [0, 1].
Per-synthesis options that may override instance defaults.