Sound - Doppler Effect

The change in frequency of sound due to relative motion between a source and a listener is called the Doppler Effect.

The observed sound frequency for a listener can be expressed as:

fr = fs (c + vr) / (c + vs)

Where:

fr = frequency observed by the receiver (Hz)
fs = frequency emitted from the source (Hz)
c = speed of sound (m/s)
vr = velocity of the receiver relative to the medium (m/s) - positive if moving towards the source
vs = velocity of the source relative to the medium (m/s) - positive if moving away from the receiver

Source Frequency (Hz)	Speed of Sound (m/s)	Receiver Velocity (m/s)	Source Velocity (m/s)	Observed Frequency (Hz)
1000	343	0	0	1000
1000	343	55.6	0	1162
1000	343	-55.6	0	838
1000	343	0	55.6	882
1000	343	0	-55.6	1163