Indicators for Non-Stationary Sounds

Indicators for non-stationary sounds allow you to assess the perception of sounds that vary over time. The computation profile includes a standard ISO532-1 loudness model dedicated to time-varying sounds. The computation profile also includes sharpness and percentile indicators.

Note: The ISO532-1 indicator was updated from ISO532B in the 2021 R2 release.

The Indicators for non-stationary sounds profile calculates the following indicators:

  • Instantaneous loudness for non-stationary sounds according to Zwicker and Fastl’s model is calculated every two ms in a way similar to ISO532-1 Loudness.Temporal masking, that is the possibility that a sound mask a weaker sound occurring very shortly before or after, is also taken into account. The result is expressed in both sone and phon according to the same formula as in the ISO532-1 standard.
  • Maximum loudness ISO532-1 (sone|phone) is the maximum value of the instantaneous loudness.

  • Percentile indicators (N5 (sone), L5 (phone), N10 (sone), L10 (phone)) are recommended by Zwicker to estimate the overall loudness of a sound that slowly varies over time.

    Percentile indicators are calculated on the basis of the instantaneous loudness. N5 (resp. L5) is the loudness in sone (resp. loudness level in phon) that is exceeded during 5% of the time. N10 (resp. L10) is the loudness in sone (resp. loudness level in phon) that is exceeded during 10% of the time.

  • Sharpness vs. time (acum) is the sharpness calculated at every two ms of the signal. A lowpass filter with a 8-Hz cutoff frequency is then applied to smooth out these sharpness values over time. In each time frame, the calculation is the same as for stationary sounds.
  • Max Sharpness (acum) is the maximum value of the sharpness vs. time curve.
  • DIN45692 Sharpness vs. time (acum) is the sharpness according to the DIN45692 standard calculated at every two ms of the signal. A lowpass filter with a 8-Hz cutoff frequency is then applied to smooth out these sharpness values over time. In each time frame, the calculation is the same as for stationary sounds.
  • Max DIN45692 Sharpness (acum) is the maximum value of the sharpness according to the DIN45692 standard vs. time curve.
  • Roughness vs Time
  • Fluctuation Strength (vacil)
  • Specific Fluctuation Strength
  • Tonal Audibility ISO1996-2:2007 (dB) vs time
  • DIN45681 / ISO/PAS 20065 Tonality vs time
  • Average Tonality Aures (tu) vs time
  • Articulation Index vs Time ANSI S3.5-1969
  • Automotive Articulation Index vs Time (%)
  • Frequency vs time ECMA-418-2 / ECMA74-G
  • Psychoacoustic Tonality ECMA-418-2 / ECMA74-G (tuHMS) vs time