Use this calculation for a first-order acoustics estimate when the stated geometry, propagation model, averaging convention, reference quantity, and SI units match the measurement or design problem.

Source Hertz

A finite measured or assumed value greater than or equal to 0, expressed in Hz.

Sound Speed Meters Per Second

A finite measured or assumed value greater than or equal to 0, expressed in m/s.

Observer Speed Meters Per Second

A finite measured or assumed value greater than or equal to 0, expressed in m/s.

The implemented rule is: Observed frequency for a listener moving toward a stationary source through still air.^[1]

Observed Hertz

The calculated observed hertz, expressed in Hz.

This is an idealized calculation rather than a complete acoustic simulation or measurement. Reflections, boundary conditions, directivity, damping, frequency dependence, near-field behavior, background noise, transducer response, temperature, humidity, and geometry can change a real result.

Confirm important results with calibrated measurements or a model that includes the actual geometry, materials, boundaries, source directivity, and frequency-dependent losses. Preserve the reference quantity and weighting whenever a result is expressed in decibels.

• Doppler Approaching Frequency

  Observed frequency from a source approaching a stationary listener through still air.

• Doppler Receding Frequency

  Observed frequency from a source receding from a stationary listener through still air.

• Angular Frequency Calculator

  Angular frequency in radians per second from frequency in hertz.