Sound level meters need time averaging to estimate varying pressure levels

Evidence

The frequency weighting is not the only factor that must be considered when using a sound level meter. In order to obtain an estimate of the sound pressure level, it is necessary to average over at least one cycle, and preferably more, of the sound waveform. Thus most sound level meters have slow and fast time response settings. The slow time response gives an estimate of the average sound level, whereas the fast response tracks more rapid variations in the sound pressure level. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 637

Categorization

• DEFINE: Explains the physical reason slow and fast meter settings exist.
• corroborated: 3 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 637
• XREF: connects to: Leq integrates squared pressure over time to yield an equivalent constant sound level — David Howard, Jamie Angus, coustics and Psychoacoustics, 629; Perceived loudness of time-varying sounds tracks near-peak levels, not averages; Sound level meters trade average level against tracking speed via time response. — David Howard, Jamie Angus, coustics and Psychoacoustics, 627

Broader Connections

• Leq integrates squared pressure over time to yield an equivalent constant sound level #expands (0.90) — David Howard, Jamie Angus, coustics and Psychoacoustics, 629
• Perceived loudness of time-varying sounds tracks near-peak levels, not averages #contradicts (0.75)