No sound is required for Halo Sport's stimulation function. There are, however, some different alert tones which come from the headset to indicate various stimulation events.
A short tone comes from the headset when a Neuropriming session starts (short 2-tone beep) and is completed (short 4-tone beep). Also, if there are any contact or connection complications during the Neuropriming session, the headset will produce a tone to indicate that priming has stopped. If this happens, the alert tone will continue until the problem has been resolved. Check the Halo Sport App for further instructions.
If your headset has lost contact with your head, check out our poor contact tips article for help establishing good contact.