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.

Directivity Factor

A finite measured or assumed value greater than or equal to 0.

Room Constant Square Meters

A finite measured or assumed value greater than or equal to 0, expressed in m2.

Distance Meters

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

The implemented rule is: Ideal direct-to-reverberant sound-energy ratio in dB at distance r, using Q R/(16πr²).^[1]

Ratio Decibels

The calculated ratio decibels, expressed in dB.

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.

• Absorption Required For Target Rt

  Metric Sabine equivalent absorption area required for a target RT60: 0.161V/T.

• Air Absorption Loss

  Atmospheric attenuation in dB from a specified frequency-dependent attenuation coefficient and path distance.

• Area Weighted Absorption Coefficient

  Area-weighted mean absorption coefficient of two surface materials.