Doppler Effect (Sound) Calculator
Find the observed frequency and wavelength shift from source frequency, speed of sound, and source and observer speeds. Approach or recede.
Input
Enter the source frequency, speed of sound, the source and observer speeds, and whether they approach or recede to compute the observed frequency and wavelength change.
Original frequency emitted by the source
Default is 340 m/s in standard air
Speed at which the source moves (positive)
Speed at which the observer moves (positive)
Choose whether source and observer get closer or farther apart
Result
Observed frequency
467.5Hz
Heard about 27.5 Hz higher than the source.
Wavelength change
-0.045455 m
Observed wavelength
0.727273 m
Speed of sound
340 m/s
Observed frequency f_obs = f × (c ± v_observer) / (c ∓ v_source). Wavelength is λ = c / f.
How it works
- The observed frequency is f_obs = f × (c ± v_observer) / (c ∓ v_source), where c is the speed of sound and v are the speeds.
- On approach, the observer speed is added in the numerator and the source speed is subtracted in the denominator. On recede the signs are reversed.
- The default speed of sound is 340 m/s, roughly standard air at about 15 degrees Celsius. It varies with temperature, so adjust the input as needed.
- Enter speeds as positive values and use the approach or recede option to set the direction. The medium (air) is assumed to be at rest.
- Wavelength is λ = c / f, and the wavelength change is observed wavelength minus original wavelength. On approach the formula breaks down when the source speed reaches the speed of sound.
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Doppler Effect (Sound) Calculator