Instructs the speech synthesizer on how to generate the
output audio content. If this audio config is supplied in a
request, it overrides all existing text-to-speech settings
applied to the agent.
int
The synthesis sample rate (in hertz) for this
audio. If not provided, then the synthesizer
will use the default sample rate based on the
audio encoding. If this is different from the
voice's natural sample rate, then the
synthesizer will honor this request by
converting to the desired sample rate (which
might result in worse audio quality).