how come when you speed up an audio track, the pitch also (usually) goes up?
In: 38
Pitch depends on the frequency of the sound. When you draw out a sound wave, it goes up and down at varying times and varying amplitudes.
Let’s just think of a simple sine wave. It goes up and down repeatedly to the exact same intensity and at the exact same time interval all throughout. If you played a sound like this, it would be a simple tone with a pitch, and not much else going on because it’s a simple one.
If we played this sine wave faster, what we’re effectively doing is taking this sine wave and squishing it from the sides to make it fit in a smaller amount of time. This changes the frequency of it because each peak happens closer together than it did before. All sine waves are the same shape, but squishing and stretching them will change the frequency, and that changes the pitch that you’d hear from it in a speaker.
All sounds will work similarly. Squish it to make it fit in a smaller time frame, and the frequency goes up to keep everything going faster, and faster frequencies in sound mean higher pitches to our ears.
With computers and certain software, you can speed up sound without changing the pitch, because it actually changes the entire shape of the wave to make all the same pitches happen in the same order, but faster. But that’s relatively advanced and uses a lot of calculus
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