ATAcoustic Toolbox

Propagation

Doppler Shift

Calculate the observed frequency and hear a source pass a stationary receiver.

Frequency calculation

Positive velocities point toward the other object; negative velocities point away.

fR = fS · (c + vR) / (c − vS)

Pass-by simulation

A source moves along a straight path past a stationary receiver.

Source frequencyObserved frequency

Keep the listening level moderate. The preview uses a synthetic tone or band-limited noise, not a recording of a vehicle.

What you hear

As the source approaches, wavefronts arrive closer together and the perceived pitch rises. After the closest point, they spread out and the pitch falls. A real pass-by changes continuously because only the velocity component along the line of sight produces the Doppler shift.

Model limits

The calculator uses the classical Doppler equation for sound in still air and subsonic motion. The pass-by preview includes the changing radial source velocity and a simple distance-dependent level change. Wind, reflections, engine modulation and propagation delay are not included.