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.

Level 500 Hz

A finite measured or assumed value, expressed in dB.

Level 1000 Hz

A finite measured or assumed value, expressed in dB.

Level 2000 Hz

A finite measured or assumed value, expressed in dB.

Level 4000 Hz

A finite measured or assumed value, expressed in dB.

The implemented rule is: Arithmetic mean of speech-band octave levels at 500, 1000, 2000 and 4000 Hz.^[1]

Sil Decibels

The calculated sil 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.

• Calibration Level Offset

  Signed level calibration offset to add to measured readings to match a reference calibrator.

• Day Night Level Dnl

  24-hour day-night level from representative 15-hour day and 9-hour night Leq, with a 10 dB night penalty.

• Equivalent Continuous Level Leq

  Two-interval equivalent continuous sound level from each interval's level and duration.