Clipping
The signal tried to go louder than the maximum, so its peaks got chopped flat. That harsh crackle when audio hits the red.
See it
What it is
Every digital signal has a hard ceiling: 0 dBFS. When a waveform tries to go past it, the tops and bottoms get sliced flat, and those flat edges are heard as crackle, fuzz, and harshness. That is clipping. It shows in the waveform as blocky plateaus where a rounded peak should be, and in the meters as red.
Two flavors matter. Analog clipping happens at the mic preamp when you turn the input gain up too far, and it is baked into the file forever. Digital clipping happens later, when plugins or a loud master push past the ceiling, and you can usually just turn something down. Fix the first with better gain staging, the second with a limiter or a lower fader.
Gotcha: pulling the volume down after the fact does not undeclip anything. The clipped file just gets quieter and still sounds crunchy, because the peak information was thrown away at record time. Declipper tools guess the missing curve and only rescue brief, mild damage. Related trap: a mix that never clips in your DAW can still clip on playback, which is the true peak problem.
Ask AI for it
Check this audio for clipping: find every sample at or above 0 dBFS and every flat-topped plateau in the waveform, and report the timestamps. Then work out whether the clipping comes from the current processing chain or is baked into the source recording. For chain overload, lower the gain feeding the offending plugin and rerender; do not just pull the fader after it. For baked-in clipping, run a declipper on the short damaged regions only, leaving the rest of the file untouched. Use a true-peak limiter at -1 dBTP solely to stop new overs on export, never as a repair for damage that already happened.