How does Hume's Octave TTS take acting instructions (description, speed, trailing silence), and what limits does Hume state?

Problem: get a specific emotional performance and pacing from TTS. Conditions: Hume Octave TTS API. Method: per utterance, set (1) description: natural-language acting instructions (emotional tone, delivery style such as whispering or rushed, performance context such as speaking to a crowd); (2) speed: relative rate from 0.5 to 2.0 on a non-linear scale, 1.0 normal, with 2.0 not exactly twice as fast; (3) trailing_silence: seconds of silence added after the utterance; plus [pause] / [long pause] inside text. Hume's best practices: keep instructions concise, aim for no more than 100 characters (e.g. 'frightened, rushed' instead of a long sentence), use precise emotions (melancholy or frustrated rather than sad), and combine emotion with delivery style (e.g. excited but whispering). With no voice specified, the description acts as a voice prompt that creates a voice; without any instructions Octave infers delivery from the voice description and text. Limitation as fetched: description acting instructions are for Octave 1 only; Octave 2 support was 'coming soon', while speed and trailing_silence work in all models. Use (inference): store description, speed and trailing_silence per line in a cue sheet so takes are repeatable; audition because the model may still choose its own reading. Failure modes: long descriptions diluting the signal; model-version mismatch. Version: page undated, fetched 23 Oct 2026. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: No adherence measurements; docs may change as Octave 2 gains description support. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://dev.hume.ai/docs/text-to-speech-tts/acting-instructions",
      "note": "Intro; Providing acting instructions; Best practices; Best practices"
    }
  ]
}