A noise level that fluctuates over a range greater than 10 dB during observation is classified as impulsive.
Impulsive sounds, such as gun shots, hammer blows, explosions of fireworks or other blasts, are sounds that significantly exceed the background sound pressure level for a very short duration.
- There is no clearly defined psychoacoustic concept of impulsiveness
- Impulsiveness is related to rapid onsets in signal
- If the repetition rate of impulses is >10-15 Hz, roughness is perceived
- In noise control, impulsiveness is considered to increase hearing damage risk compared to non-impulsive sound of same energy
- Measurements with the meter set to ‘Fast’ response do not accurately represent impulsive sounds.
C-weighted levels have been found useful for ratings of gun shots (ISO 1987).
- A measure of a short burst of sound with a rapidly changing loudness.
- The ‘crest factor’ of the pressure of a wave form peak/rms measured over a 1 sec interval.
- Kurtosis: this is a measure of how sharply the function peaks around its mode.
- Standard deviation of LAeq(10ms).
- A method for measuring impulsive noise emitted by IT and telecommunications equipment can be found in Annex E BS EN ISO 7779:2001.
Subjects: Noise & Vibration