Continuous, Intermittent, Impulsive, And Peak Noise
Canonical Definition
Sound events differ in time structure. A true-peak result is the largest instantaneous pressure captured by a sufficiently fast, wide-range, unclipped chain. Hearing and operational risk also depend on duration, energy, spectrum, repetition, background, position, and the measurement method.
Classify The Event
| Event | Example | Required record |
|---|---|---|
| continuous | steady sine, noise, or sustained music | level history, duration, spectrum, dose, and equipment temperatures |
| intermittent | repeated demonstrations with quiet intervals | each on/off period and cumulative exposure |
| burst | one-to-several-second competition tone | frequency, ramp, hold, peak, equivalent level, repetition, and recovery |
| impulsive or impact | very rapid high-level transient | true peak, waveform, duration, energy, repetition, and suitable high-bandwidth instrumentation |
The 140 dB Peak Reference
OSHA's noise standard and current interpretation treat exposure above 140 dB peak as an extreme hazard. That number is not a target, a safe occupancy permission, or a complete risk model. Repetition, energy, continuous background, protection, and the validity of the measurement still matter.
For peak impulse measurement, OSHA's current interpretation calls for an unweighted or Z-weighted true-peak result from appropriate equipment.
Car-Audio Burps Are Not Automatically Gunshot-Like Impulses
A narrowband low-frequency event held for one or more seconds can be brief without having the rise time and waveform of an impulse. Record it as the event it actually is. Use hearing-exposure, true-peak, competition, electrical, thermal, and structural measurements as separate channels of evidence.
Instrument Clipping
If any stage clips, the displayed plateau can understate the event and corrupt dose, maximum, and peak results. Use a suitable microphone or pressure sensor and preserve overload flags.