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Mihsaba›Doppler Effect Calculator

Doppler Effect Calculator

Calculate observed sound frequency when source and observer move toward each other through a stationary medium.

Positive speeds here are defined as motion toward each other; receding motion requires the corresponding sign convention.

How to use

Relative motion of source and observer changes the spacing of wavefronts arriving at the observer, shifting the perceived sound frequency.

  1. Enter source frequency and wave speed.
  2. Enter observer speed toward source.
  3. Enter source speed toward observer.
  4. Review observed frequency and shift.

How it is calculated

f′=f(c+vₒ)/(c−vₛ)

Example

A 1000 Hz source moving toward a stationary observer at 20 m/s in air with c=343 m/s produces an observed frequency above 1000 Hz.

Important notes

This form is for sound in a stationary medium at classical speeds. It is not the relativistic Doppler formula for light.

Frequently asked questions

Why must source speed stay below c?

This classical form becomes singular as the denominator approaches zero and does not cover supersonic source behavior.

What if the source recedes?

Use the appropriate opposite sign in the general formula.

Is observer speed always positive?

Only in this calculator’s simplified convention: positive means toward the source.