Why does a siren sound higher-pitched as it approaches?

As the source moves toward you, each successive sound wave is emitted slightly closer, compressing the wavelength and raising the perceived frequency — the classic Doppler effect.

Doppler Effect Calculator

Calculate the perceived frequency shift of a sound wave when its source is moving toward a stationary observer, using the Doppler effect formula.

Inputs

Results

Observed Frequency: 547.92 Hz

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Formula

f_observed = f_source × (v / (v − v_source))

Learn How This Works

Light and Sound Phenomena: Refraction, Doppler Shift, and Density

Refractive index, the Doppler effect, sound travel time, and specific gravity — four calculations describing how light and sound behave and how substances compare to water.

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