Activate the VRChat Listener, you can enable Activate VRChat Listener on Start to enable the feature automatically each time. (You still have to click the big "*Activate VRChat Listener button** the first time).
Add a bool to your avatar for /avatar/parameters/DoSpeechToText
Speech to Text will be activated whenever a bool is sent (If the method can be toggled then sending another true bool would also deactivate the speech to text)
Additionally, /avatar/parameters/stt_listening is a parameter sent automatically by TTS Voice Wizard and can be used to determine if Speech to Text is currently listening or not.