Good question, I've also wondered about this.I'm curious how Lenire can work off signal timing based on the very precise millisecond timing between sounds and tongue zap...
...but then uses Bluetooth headphones? Which has a very high latency in hundreds of milliseconds and it's not a constant latency too. It fluctuates and very difficult (if not impossible) to compensate for on the tongue zapper end.
Why didn't they just use a wired headphone with no latency?
Not saying it doesn't work, but as an electrical engineer I'm a bit skeptical on this detail.
They are very strict about the headphone: there is one specific model that they used in both the trials and in the finished devices. This comes up in the Q&A, too. Maybe this specific headphone has been selected for low jitter (so stable latency).
Also, because the device is tethered to you by the tonguetip electrode, and you are stationary during treatment, the headphone is very close to the device and the distance is constant.