Many headphones can send commands to its device, such as Airpods, with a single press to pause or resume, double press to play the next track, and triple press to play the previous track.
Using this feature, we can use the headphones as a morse transmitter.
https://etherdream.github.io/headphone-morse-transmitter/
demo.mp4
If you're using an Airpod, a single press sends a dit (.) , a double press sends a dah(-), and a triple press deletes the previous character.
When the delay time is reached, the dit and dah codes in the input will be converted to a letter or number.
Shorter delays allow faster input, but also increase the chance of errors.
Known issues: Firefox is not supported yet.