Intermittent sound

nNoise that occurs at regular or irregular time intervals and is such that the duration of each such occurrence is more than about 5 s. Note 1 to entry: Adapted from ISO 1996‑1:2003. Note 2 to entry: This definition does not apply to a whole pass-by event. Note 3 to entry: Intermittence should be assessed relatively to the duration of the event. Note 4 to entry: Examples: compressor, cooling fans.