Sound Pressure Level

Sound Pressure Level

The term most often used in measuring the magnitude of sound. It is a relative quantity in that it is the ratio between the actual SOUND PRESSURE and a fixed reference pressure. This reference pressure is usually that of the THRESHOLD OF HEARING which has been internationally agreed upon as having the value .0002 dynes/cm2.

SPL may be measured with a SOUND LEVEL METER weighted according to a specific frequency response pattern and termed SOUND LEVEL. The electroacoustic equivalent to SPL is measured with a VU METER.

— Source: SOUND PRESSURE LEVEL (SPL) http://www.sfu.ca

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

— Source: http://www.diracdelta.co.uk