Hello,
I have an audio recording with increased speed, probably ~ 2x faster than “normal” . Is there a way to somehow determine the “original” speed of recording and hear it undistorted?
To get an approximate estimation of the correct speed, you could try adjusting the “Play at Speed” control (https://manual.audacityteam.org/man/play_at_speed_toolbar.html).
Note that this control does not change the track audio, it is only a playback control.
Once you have determined the correct speed, you can change the track audio by applying the “Change Speed” effect (https://manual.audacityteam.org/man/change_speed.html)
You may be able to determine the exact speed by considering where the audio came from. For example, if it is a recording from vinyl, it could be due to the record being played at 45 rpm when it should have been played at 33 1/3 rpm, or if it was a converted file from a digital voice recorder, it could be due to the sample rate being changed from 22050 Hz to 44100 Hz.