Basic Concepts of Sound
Contents:DefinitionsdB ConversionSound FieldsdB ±dB
BA 7666-11, 11
Range of Sound Pressure Levels
Sound Pressure, p
[Pa]
1001010.10.010.0010.000 10.000 01
Sound Pressure Level, Lp140120100806040200
[dB]
BA 7666-11, 12860508/2
dB –decibel
pμPaLp= 20 log dB re 20 p0(p0= 20 μPa = 20 ×10-6 Pa)Ex. 1:p=1Pa
Lp= 20 log
1
20×10?6
Ex. 2:p= 31.7 Pa
Lp= 20 log
31.720×10?6
= 20 log 50 000= 94 dB
= 20 log 1.58 ×10-6= 124 dB
BA 7666-11, 13
Perception of dBs
Change in Sound Level (dB)35101520Change in Perceived LoudnessJust perceptibleNoticeable differenceTwice (or 1/2) as loudLarge changeFour times (or 1/4) as loudBA 7666-11, 14
Conversion to dB using Charts
Lp
200
dB re 20 μPa150
100
94 dB50
0
0.00010.010.1110100100010 000Pressure[Pa]p0 = 20 μPaBA 7666-11, 15
声学基本概念 - 图文
