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.

Path Difference Meters

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

Wavelength Meters

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

The implemented rule is: Barrier Fresnel number 2δ/λ from extra sound-path length and wavelength.^[1]

Fresnel Number

The calculated fresnel number.

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.

• Barrier Path Difference

  Extra diffracted sound-path length around a barrier versus direct line-of-sight distance.

• Wave Number Calculator

  Angular wave number in radians per metre from positive wavelength.

• Angular Frequency Calculator

  Angular frequency in radians per second from frequency in hertz.