A method of describing sound levels that vary over time, resulting in a single decibel value which takes into account the total sound energy over the period of time of interest.
- Noise level: a physical scale for the description of environmental noise, which has a relationship with a harmful effect, expressed in decibels (dB).
The standard noise level indicators are:
- Lden (day-evening-night noise indicator): for overall annoyance;
- Lday (day-noise indicator): for annoyance during the day period;
- Levening (evening-noise indicator): for annoyance during the evening period;
- Lnight (night-time noise indicator): for sleep disturbance.