Sound levels and band totals#
In absolute source mode, the supplied octave-band levels define the source’s on-axis sound pressure level at a reference distance of 1 m. Predicted receiver levels use this saved source reference. Relative source mode does not establish absolute SPL.
Sum only levels with compatible references.
Energy-ratio level conversion
Receiver levels use the saved source reference. Absolute mode uses on-axis SPL at 1 m; relative mode does not establish absolute SPL.
- L, Lref
- Received and reference levels on the same defined basis (dB)
- E, Eref
- Received and matching reference energy (same energy unit)
Band totals and A-weighting#
Logarithmic band summation
Overall levels combine compatible octave-band energies on a common reference basis.
- Ltotal
- Combined level (dB)
- Lᵢ
- Band level on a common reference basis (dB)
Overall unweighted and A-weighted level estimates require usable results in all eight octave bands, from 63 Hz to 8 kHz. Available individual bands can still be displayed when an overall level is unavailable. The A-weighted result applies octave-band corrections and remains an approximation.
Finite response can omit energy and must retain its associated qualification.
Sound strength (G)#
Sound strength (G) expresses received sound strength in decibels relative to the same omnidirectional source at 10 m in a free field. Available for eligible omnidirectional source configurations.
Sound-level coverage#
Sound-level coverage describes the difference between the highest and lowest eligible levels across listening positions, for unweighted and A-weighted estimates. It applies to the sampled positions.
For the statistical direct/reverberant balance, see Critical distance.