Check your microphone right in the browser. Speak and the input level moves in real time, telling you whether you're too quiet, in a good range, or loud enough to distort. Record a few seconds and play it back to hear exactly what others hear.
Your input may be set to a different microphone — try switching it in the device list above. If that doesn't help, check your operating system's sound settings for a muted mic or blocked app access.
Nowhere. It lives only in your browser's memory and disappears when you leave the page. You can download it yourself if you want to keep it.
When the level touches 0 dB the signal clips and breaks up. Lower the microphone input volume in your system settings, or move slightly further from the mic.