This is a complete transmitter and receiver running in your browser. Speak into your microphone or play a sample, and watch a real carrier get modulated, cross a noisy channel, and get demodulated again — while you listen to every stage.
The carrier sits in the audio band (a few kHz) instead of a few MHz, so you can hear the RF. Every equation is the real one.
Headphone users: start with the volume low.