Decay times

Decay times in the Info menu performs an evaluation of reverse-time integrated impulse responses (IIR). If no IIR is present in the memory, the menu for IIR processing is launched automatically.

At first the parameters to be displayed are to be selected via the Select/Select parameters submenu of the Decay times menu.

The analysis is performed according to DIN EN ISO 3382-1:2009 and DIN EN ISO 3382-2:2008. In addition to decay times for the various intervals, the following evaluations and information can be produced:

  • channel tag: shows the associated channel number from before the filtering, so the results can be associated to the original channels
  • fm nom. [Hz]: nominal band centre frequency according to DIN EN 61620
  • fm [Hz]: exact band centre frequency according to DIN EN 61620
  • C(...): degree of curvature according to ISO 3382-2:2008, Annex B3. For example C(T20-30) is the degree of curvature for the T20 interval compared to the T30 interval, etc. Typical values are between 0 and 5%, values beyond 10% indicate deviations from the linear shape
  • x: degree of non-linearity according to ISO 3382-2:2008, Annex B2. For the respective evaluation interval the squared correlation coefficient is calculated. E.g. x30 calculates a measure for the deviation from the linear regression curve between -5 and -35dB. In contrast to the curvature C, x also detects fluctuations. The value is given in per mil. A value around 0 means no deviation, 1000 is maximum deviation. Typical values for sound IIRs are between 0 and 5 per mil.

Via the copy table to spectrum button the displayed RT values are copied as spectra to multiple channels in the frequency domain.