2001
f c
k R T 340 m/s 5000 m/s 3320 m/s 1450 m/s 500 m/s
20 ~ 20000Hz 20 Hz 20000 Hz
2:131.3(31.25)63(62.5)125250500100020004000 8000 Hz
WW IW/m2 pPa
: :
() p0=210-5 PaI0=110-12 W/m2 p=20 PaI=1W/m2
L dB 2105Pa ~ 20Pa
(IPW ) n L1
10 lg2 = 3 dB
10~15 dB
()AE
11
Q R
S arrLpLpLWLWS0f IIV4QAB
1000 Hz Phon
A 4070100ABC AA 40A
A
NR(Noise Rating) A NRISO LA =NR+5 dB
NC NC(Noise Criterion Curves)Beranek19571968ISO NR LA =NC+10 dB NCNR5
PNC PNC(Preferred Noise Curves )NC PNC=3.5+NC
NR(dB)AdB(A) 35~45 40~50 40~45 40~50 35 40 45 50 50~55 55~60 40~45 40~50 30~45 35~50 30 35 25 30 20 25 35 40 35 40
a
25mm25mm
=11.7cm=3.4m
()
Sound Mask 1
2
T
f f 0
0 dB 0 dB? NRNC