Dr. Weiss wrote back and asked if it would be possible to produce any major (or minor) chord of higher or lower frequency using the Doppler shift.

(You can read the previous post here.)

The problem with this is that once we hit 340 m/s, we are at the sound barrier. As I understand it, once we hit the sound barrier the waves are compressed against each other so that we no longer hear them as a specific pitch, but as a sonic boom. So, how far can we slide?

Using our trust formula, if I take an A 440Hz and travel at 340 m/s away from it:

440Hz*340m/s ÷ (340m/s + 340 m/s) = x
149600 ÷ 680 = 220 Hz

Miraculously convenient, it appears that at the precise point at which you would perceive a pitch exactly one octave below where it is played, you would create a sonic boom instead and probably blow out someone’s ear drums. So, don’t try it at home.