Velocity of sound relative to air = v

Frequency of emitted sound = f

Apparent frequency of received sound = f’.

If the source moves with a velocity of magnitude v_s (relative to the air) then the velocity of the waves relative to the source is (v±v_s).

In general,

so in this case,

The apparent frequency of the sound, f’, as measured by the observer, will be equal to v/.

Therefore, the apparent frequency is given by

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