Doppler Shift: Ambulance Siren (440 Hz) Receding at 30 m/s
An ambulance siren at 440 Hz moving away at 30 m/s is heard at approximately 403 Hz — noticeably lower than the source.
How to use this tool
- Enter source frequency f₀, source velocity vₛ, observer velocity vₒ and wave speed v in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your observed frequency and the full breakdown beneath it.
As an ambulance passes and moves away, its siren drops in pitch because sound waves are stretched by the increasing distance.
Frequently asked questions
- What is the speed of sound used here?
- 343 m/s at 20 °C in air at sea level. It varies with temperature: roughly v ≈ 331 + 0.6×T(°C) m/s.
- Does the Doppler effect apply to light too?
- Yes, but the relativistic formula must be used. The astronomical redshift of distant galaxies is a Doppler-related phenomenon.