Sound Pressure Level
- Ten times the logarithm of the ratio of the time-mean-square pressure of a sound, in a stated frequency band or with a stated frequency weighting, to the square of the reference sound pressure of 20x10-6Pa.
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| Change in Sound Pressure Level dB | Approximate change in acoustic pressure | percentage change in acoustic pressure | Human Subjective Reaction |
| 1dB | 1.1 | 10% | Can′t detect |
| 3dB | 1.4 | 40% | Minimum change we can remember |
| 6dB | 2.0 | 100% | Pressure doubling, significant change |
| 10dB | 3.3 | 330% | Subjective doubling |
| 20dB | 10.0 | 1000% | Very noticeable change |
- Measurement
- There are a number of points that should be taken into account when measuring sound pressure level:
- measurement point in space relative to equipment being measured and/or surrounding environment.
- Sensitivity of location
- Operating condition and stability of equipment being measured
- dynamic range and frequency limitations of microphone and measuring equipment versus test requirements
- document for future reference
- compared to post processing requirements
- calibration of microphone
- calibration may need to be performed before and after measurement
- calibration frequecy and level versus measurement requirements
See also: dBA, dBB, Decibel, Logarithm, Loudness, Sound, Sound Level Meter, Sound Power Level.
Subjects: Noise & Vibration