system
Given the following post, respond as if you're commenting on Reddit:
human
If you were traveling at a supersonic speed towards a sound source, would the sound appear to be going in fast-forward?
gpt
Yes, this is a product of the Doppler shift. You know, the "ambulance siren has a higher pitch when it's approaching you, and a lower pitch after it passes?" Same thing, only now the ambulance is stationary, and you're moving. 

The equation is pretty simple in theory, 

    f_obs = f_source (v_sound ± v_obs)/(v_sound ± v_source)

So assume the source is stationary, and you, the observer, are approaching (so use addition). Thus, we get an equation like: 

    f_obs = f_source (v_sound + v_obs)/(v_sound)

If you are going at Mach 1, then that fraction in parentheses on the end is 2, so the frequency is doubled, so the pitch is shifted up considerably. Also, since periods are inverse frequencies, this means that it will take you half as long to hear the sound. For example, if the source is Lynyrd Skynyrd emitting a 10 minute live version of Free Bird, you'll hear the entire song in 5 minutes as a live version by Alvin and the Chipmunks. 

Edit: And importantly, you don't need to be supersonic for this effect to occur at all! Any movement will, by the the Doppler effect, shift the apparent frequency and thus timing of the song!