Music & Acoustics

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Doppler Pitch Shift

Observed pitch changes as a source moves toward or away.

Formula

f' = f\,\frac{v + v_o}{v - v_s}

Variables

f'Observed frequency (Hz)

fSource frequency (Hz)

vSpeed of sound (m/s)

v_oObserver speed

v_sSource speed

Example

Siren 700 Hz, source 30 m/s toward you: f' ≈ 767 Hz

Did You Know?

The drop in pitch as an ambulance passes is the everyday proof of the Doppler effect.

music doppler pitch

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