Doppler Effect

Watch the ambulance pass — see the wavefronts crowd ahead, stretch behind, and hear the siren's pitch shift.

Tap to Begin

The Equation

f_o = f_s · (c + v_o) / (c − v_s)

Source

600 Hz

Heard

600 Hz

Shift +0 Hz

Waveform

Source Heard

Controls

Source speed (v_s)

60m/s

Source frequency (f_s)

600Hz

Observer position (x_o)

Observer velocity (v_o)

0m/s

The ambulance emits circular sound wavefronts as it drives. With v_s > 0 the rings bunch ahead and spread behind.

The observer hears each ring as it sweeps past. Drag them along the road to reposition.

Speed of sound c = 343 m/s. Rings are stylised; pitch is from the real Doppler formula.