Speed a recording up to get through it faster, or slow it down to catch every word — with or without the chipmunk effect.
Keeping the pitch uses a grain-based time stretch. It is excellent on speech and good on most music; extreme settings past about 2× can sound slightly watery.
The Speed Changer makes a recording play faster or slower — and, if you want, does it without turning everyone into a chipmunk.
Left to itself, playing audio faster raises its pitch, exactly like spinning a record too quickly. With Keep the original pitch ticked, the tool instead chops the sound into tiny overlapping grains and lays them back down closer together, sliding each one to the point where it lines up best with what came before. The result is speech at 1.5× that still sounds like the same person.
Untick it and you get the honest record-player effect, which is what you want for sped-up or slowed-down music edits. Either way the file is processed as raw samples, so a podcast episode speeds up in seconds rather than having to play all the way through.
Speed and pitch are normally locked together — play something twice as fast and it sounds an octave higher. Keeping the pitch means the tool rebuilds the audio so the pace changes but the voices and notes stay where they were.
A little, and more the further you go from normal speed. Between about 0.7× and 2× it is very hard to hear on speech. Past that it can sound faintly watery or flutter on sustained musical notes.
From a quarter speed to four times speed. Extremes are most useful for sound design; for listening, most people settle between 1.25× and 1.75×.
Because it is a different length. A file sped up to 2× has half as much audio in it, so it is roughly half the size.
Yes — that is the Pitch Shifter, a separate tool linked below. It uses the same engine in the opposite direction.