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Absorption and Velocity of Sound in Still Air
The tables of data below refer only to the temperature 20°C (68°F). Values are provided for relative humidities of 0%, 30%, 50%, 70% 90%, and 100%.
Frequency (Hz)
Absorption (dB/1000 ft)
Absorption (dB/km)
Absorption (dB/s)
Velocity (1000 ft/s)
Relative Humidity = 0%
20
0.154
0.51
0.174
1.126892
40
0.327
1.07
0.368
1.127013
50
0.384
1.26
0.433
1.127050
63
0.436
1.43
0.491
1.127085
100
0.509
1.67
0.573
1.127131
200
0.560
1.84
0.631
1.127161
400
0.596
1.96
0.672
1.127169
630
0.645
2.11
0.727
1.127171
800
0.692
2.27
0.780
1.127172
1250
0.861
2.82
0.970
1.127172
2000
1.262
4.14
1.423
1.127173
4000
2.696
8.84
3.030
1.127178
6300
4.541
14.89
5.118
1.127182
10000
8.013
26.28
9.032
1.127184
12500
10.918
35.81
12.306
1.127186
16000
15.901
52.15
17.923
1.127187
20000
22.978
75.37
25.901
1.127187
40000
81.405
267.01
91.759
1.127188
63000
196.544
644.66
221.542
1.127188
80000
314.677
1032.14
354.700
1.127188
Frequency (Hz)
Absorption (dB/1000 ft)
Absorption (dB/Km)
Absorption (dB/s)
Velocity (1000 ft/s
Relative Humidity = 30%
20
0.009
0.03
0.010
1.127976
40
0.034
0.11
0.038
1.127980
50
0.051
0.17
0.057
1.127984
63
0.075
0.25
0.085
1.127987
100
0.151
0.50
0.170
1.127999
200
0.309
1.01
0.349
1.128023
400
0.484
1.59
0.546
1.128037
630
0.682
2.24
0.770
1.128041
800
0.868
2.85
0.979
1.128044
1250
1.552
5.09
1.751
1.128045
2000
3.333
10.93
3.760
1.128047
4000
11.856
38.89
13.374
1.128056
6300
27.626
90.61
31.164
1.128072
10000
62.493
204.98
70.498
1.128105
12500
89.659
294.08
101.148
1.128131
16000
128.814
422.51
145.324
1.128166
20000
171.847
563.66
193.879
1.128204
40000
338.710
1110.97
382.172
1.128316
63000
499.838
1639.47
563.998
1.128361
80000
635.085
2083.08
716.614
1.128375
Frequency (Hz)
Absorption (dB/1000 ft)
Absorption (dB/Km)
Absorption (dB/s)
Velocity (1000 ft/s
Relative Humidity = 50%
20
0.006
0.02
0.006
1.128795
40
0.022
0.07
0.025
1.128797
50
0.034
0.11
0.038
1.128798
63
0.052
0.17
0.058
1.128800
100
0.117
0.38
0.132
1.128807
200
0.313
1.03
0.353
1.128826
400
0.563
1.85
0.636
1.128849
630
0.734
2.41
0.828
1.128858
800
0.851
2.79
0.961
1.128860
1250
1.231
4.04
1.390
1.128862
2000
2.176
7.14
2.457
1.128865
4000
6.752
22.15
7.622
1.128867
6300
15.643
51.31
17.659
1.128871
10000
37.521
123.07
42.357
1.128881
12500
57.009
186.99
64.357
1.128890
16000
89.594
293.87
101.143
1.128903
20000
132.719
435.32
149.830
1.128922
40000
382.722
1255.33
432.101
1.129020
63000
654.606
2147.11
739.115
1.129099
80000
844.024
2768.40
953.016
1.129133
Frequency (Hz)
Absorption (dB/1000 ft)
Absorption (dB/Km)
Absorption (dB/s)
Velocity (1000 ft/s
Relative Humidity = 70%
20
0.004
0.01
0.005
1.129618
40
0.016
0.05
0.018
1.129619
50
0.025
0.08
0.028
1.129619
63
0.039
0.13
0.044
1.129620
100
0.092
0.30
0.104
1.129623
200
0.284
0.93
0.321
1.129638
400
0.611
2.01
0.691
1.129662
630
0.829
2.72
0.937
1.129673
800
0.947
3.11
1.070
1.129678
1250
1.250
4.10
1.412
1.129683
2000
1.915
6.28
2.163
1.129685
4000
5.056
16.58
5.712
1.129687
6300
11.197
36.73
12.649
1.129689
10000
26.624
87.33
30.077
1.129693
12500
40.758
133.69
46.044
1.129697
16000
65.246
214.01
73.708
1.129704
20000
99.365
325.92
112.254
1.129712
40000
339.153
1112.42
383.165
1.129770
63000
673.667
2209.63
761.137
1.129842
80000
924.481
3032.30
1044.556
1.129884
Frequency (Hz)
Absorption (dB/1000 ft)
Absorption (dB/Km)
Absorption (dB/s)
Velocity (1000 ft/s
Relative Humidity = 90%
20
0.003
0.01
0.004
1.130443
40
0.013
0.04
0.014
1.130443
50
0.019
0.06
0.022
1.130444
63
0.031
0.10
0.035
1.130444
100
0.074
0.24
0.084
1.130446
200
0.250
0.82
0.283
1.130457
400
0.621
2.04
0.702
1.130478
630
0.903
2.96
1.021
1.130493
800
1.045
3.43
1.182
1.130498
1250
1.344
4.41
1.520
1.130505
2000
1.892
6.21
2.139
1.130508
4000
4.337
14.22
4.903
1.130511
6300
9.099
29.84
10.286
1.130512
10000
21.133
69.32
23.891
1.130514
12500
32.258
105.81
36.468
1.130516
16000
51.762
169.78
58.518
1.130520
20000
79.424
260.51
89.791
1.130526
40000
290.117
951.58
327.995
1.130561
63000
629.701
2065.42
711.948
1.130612
80000
911.286
2989.02
1030.346
1.130651
Frequency (Hz)
Absorption (dB/1000 ft)
Absorption (dB/Km)
Absorption (dB/s)
Velocity (1000 ft/s
Relative Humidity = 100%
20
0.003
0.01
0.003
1.130856
40
0.011
0.04
0.013
1.130856
50
0.018
0.06
0.020
1.130857
63
0.028
0.09
0.031
1.130857
100
0.068
0.22
0.076
1.130858
200
0.234
0.77
0.265
1.130868
400
0.616
2.02
0.696
1.130888
630
0.928
3.05
1.050
1.130902
800
1.087
3.57
1.230
1.130909
1250
1.399
4.59
1.582
1.130917
2000
1.917
6.29
2.168
1.130921
4000
4.140
13.58
4.682
1.130924
6300
8.451
27.72
9.557
1.130925
10000
19.357
63.49
21.891
1.130926
12500
29.461
96.63
33.318
1.130929
16000
47.227
154.90
53.410
1.130931
20000
72.538
237.93
82.036
1.130935
40000
269.598
884.28
304.905
1.130963
63000
601.714
1973.62
680.543
1.131007
80000
888.113
2913.01
1004.492
1.131042
Information from CRC Handbook of Chemistry and Physics, 7first Edition, 1990-1991, David R. Lide Minor corrections made 8/17/2005 - thanks to Andy H.
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