Please see the "key_stop" property of the audio response: https://help.findingfive.com/api/responses.html#audio
If clicking to start recording is too cumbersome for participants, "auto_start" is also among the properties supported by the audio response. Unfortunately there's no way to bind that to a specific key or the final confirm button.
Alternatively, you may want to use the "background audio response" if you are looking for a recording solution that requires no interaction from the participants. It's important to keep them informed of being recorded though!
If clicking to start recording is too cumbersome for participants, "auto_start" is also among the properties supported by the audio response. Unfortunately there's no way to bind that to a specific key or the final confirm button.
Alternatively, you may want to use the "background audio response" if you are looking for a recording solution that requires no interaction from the participants. It's important to keep them informed of being recorded though!