Frequencies and solvers

Calculation may be at octave or third octave frequencies. Source equipment spectra is stored in either octave or third octave bands, depending on the original source. If calculation is in octaves and the original spectrum is in third octaves, then the 3 1/3 octave band levels are summed together to give the octave band level, e.g. the 200, 250 and 315 Hz 1/3 octave bands are summed to give the 250 Hz octave band level. If the calculation is in third octaves and the original spectrum is in octaves, the energy from the octave band is split evenly between the 3 1/3 octave bands (so each band receives the octave band level minus \(10 \cdot \log_{10}(3)\) , or approximately 5 dB).

The highest and lowest assessment and solver split frequencies may be changed with the up and down buttons. For octave band calculations, the lowest and highest possible bands are 16 Hz and 128 kHz, for 1/3 octave band calculations the limits are 12.5 Hz to 160 kHz.

When the button Use separate solvers for low and high frequencies is checked, the low and high frequency solvers may be individually chosen and the solver split frequency changed.

The solver can be changed between those available. For more on the available solvers, see the page Solvers.