Sound pressure level (SPL) or sound level is a logarithmic measure of the effective sound pressure of a sound relative to a reference value. It is measured in decibels (dB) above a standard reference level. The commonly used “zero” reference sound pressure in air is 20 µPa RMS, which is usually considered the threshold of human hearing (at 1 kHz).
The following table presents noise data at octave-band center frequencied for familiar residential, outdoor transportation and building activity noise sources.
|
Sound Pressure Level
|
|
Example Source
|
|
|
Home
|
63 Hz
|
125 Hz
|
250 Hz
|
500 Hz
|
1000 Hz
|
2000 Hz
|
4000 Hz
|
8000 Hz
|
dBA
|
|
Alarm Clock at 4-9 ft – Ringing
|
—
|
46
|
48
|
55
|
62
|
62
|
70
|
80
|
80
|
|
Electric Shaver at 1.5 ft
|
59
|
58
|
49
|
62
|
60
|
64
|
60
|
59
|
68
|
|
Vacuum Cleaner at 3 ft
|
48
|
66
|
69
|
73
|
79
|
73
|
73
|
72
|
81
|
|
Garbage Disposal at 2 ft
|
64
|
83
|
69
|
56
|
55
|
50
|
50
|
49
|
69
|
|
Clothes Washer at 2-3 ft – Wash Cycle
|
59
|
65
|
59
|
59
|
58
|
54
|
50
|
46
|
62
|
|
Toilet – Refilling Tank
|
50
|
55
|
53
|
54
|
57
|
56
|
57
|
52
|
63
|
|
Whirlpool, Six Nozzles – Filling Tub
|
68
|
65
|
68
|
69
|
71
|
71
|
68
|
65
|
74
|
|
Window Air-Conditioning Unit
|
64
|
64
|
65
|
56
|
53
|
48
|
44
|
37
|
59
|
|
Telephone at 4-13 ft – Ringing
|
—
|
41
|
44
|
56
|
68
|
73
|
69
|
83
|
83
|
|
TV at 10 ft
|
49
|
62
|
64
|
67
|
70
|
68
|
63
|
39
|
74
|
|
Stereo – Teenager Listening Level
|
60
|
72
|
83
|
82
|
82
|
80
|
75
|
60
|
86
|
|
Stereo – Adult Listening Level
|
56
|
66
|
75
|
72
|
70
|
66
|
64
|
48
|
75
|
|
Violin at 55 ft – Fortissimo
|
—
|
—
|
91
|
91
|
87
|
83
|
79
|
66
|
92
|
|
Normal Conversational Speech at 3 ft
|
—
|
57
|
62
|
63
|
57
|
48
|
40
|
—
|
63
|
|
Outdoors
|
63 Hz
|
125 Hz
|
250 Hz
|
500 Hz
|
1000 Hz
|
2000 Hz
|
4000 Hz
|
8000 Hz
|
dBA
|
|
Birds at 10 ft
|
—
|
—
|
—
|
—
|
—
|
50
|
52
|
54
|
57
|
|
Cicadas
|
—
|
—
|
—
|
—
|
35
|
51
|
54
|
48
|
57
|
|
Large Dog at 50 ft – Barking
|
—
|
50
|
58
|
68
|
70
|
64
|
52
|
48
|
72
|
|
Lawn Mower at 5 ft
|
85
|
87
|
86
|
84
|
81
|
74
|
70
|
72
|
86
|
|
Pistol Shot at 250 ft – Peak Impulse Levels
|
—
|
—
|
—
|
83
|
91
|
99
|
102
|
106
|
106
|
|
Surf at 10-15 ft – Moderate Seas
|
71
|
72
|
70
|
71
|
67
|
64
|
58
|
54
|
78
|
|
Wind in Trees – 10 mph
|
—
|
—
|
—
|
33
|
35
|
37
|
37
|
35
|
43
|
|
Transportation
|
63 Hz
|
125 Hz
|
250 Hz
|
500 Hz
|
1000 Hz
|
2000 Hz
|
4000 Hz
|
8000 Hz
|
dBA
|
|
Large Trucks at 50 ft – 55 mph
|
83
|
85
|
83
|
85
|
81
|
76
|
72
|
65
|
86
|
|
Passenger Cars at 50 ft – 55 mph
|
72
|
70
|
67
|
66
|
67
|
66
|
59
|
54
|
71
|
|
Motorcycle at 50 ft – Full Throttle, Without Baffle
|
95
|
95
|
91
|
91
|
91
|
87
|
87
|
85
|
95
|
|
Snowmobile at 50 ft
|
65
|
82
|
84
|
75
|
78
|
77
|
79
|
69
|
85
|
|
Train at 100 ft – Pulling Hard
|
95
|
102
|
94
|
90
|
86
|
87
|
83
|
79
|
94
|
|
Train Siren at 50 ft
|
88
|
90
|
110
|
110
|
107
|
100
|
91
|
78
|
109
|
|
Car Horn at 15 ft
|
—
|
—
|
—
|
92
|
95
|
90
|
80
|
60
|
97
|
|
Commercial Turbofan Airplane at 1 mile – From Takeoff Flight Path
|
77
|
82
|
82
|
78
|
70
|
56
|
—
|
—
|
79
|
|
Military Helicopter at 500 ft – Single Engine, Medium Size
|
92
|
89
|
83
|
81
|
76
|
72
|
62
|
51
|
80
|
|
Interiors
|
63 Hz
|
125 Hz
|
250 Hz
|
500 Hz
|
1000 Hz
|
2000 Hz
|
4000 Hz
|
8000 Hz
|
dBA
|
|
Amplified Rock Music Performance – Large Arena
|
116
|
117
|
119
|
116
|
118
|
115
|
109
|
102
|
121
|
|
Audiovisual Room
|
85
|
89
|
92
|
90
|
89
|
87
|
85
|
80
|
94
|
|
Auditorium – Applause
|
60
|
68
|
75
|
79
|
85
|
84
|
75
|
65
|
88
|
|
Classroom
|
60
|
66
|
72
|
77
|
74
|
68
|
60
|
50
|
78
|
|
Computer Equipment Room
|
78
|
75
|
73
|
78
|
80
|
78
|
74
|
70
|
84
|
|
Dog Kennel
|
—
|
—
|
90
|
104
|
106
|
101
|
89
|
79
|
108
|
|
Gymnasium
|
72
|
78
|
84
|
89
|
86
|
80
|
72
|
64
|
90
|
|
Kitchen
|
86
|
85
|
79
|
78
|
77
|
72
|
65
|
57
|
81
|
|
Laboratory
|
65
|
70
|
73
|
75
|
72
|
69
|
65
|
61
|
77
|
|
Library
|
60
|
63
|
66
|
67
|
64
|
58
|
50
|
40
|
68
|
|
Mechanical Equipment Room
|
87
|
86
|
85
|
84
|
83
|
82
|
80
|
78
|
88
|
|
Music Practice Room
|
90
|
94
|
96
|
96
|
96
|
91
|
91
|
90
|
100
|
|
Racquetball Court
|
82
|
85
|
80
|
85
|
83
|
75
|
68
|
62
|
86
|
|
Reception and Lobby Area
|
60
|
66
|
72
|
77
|
74
|
68
|
60
|
50
|
78
|
|
Teleconference
|
65
|
74
|
78
|
80
|
79
|
75
|
68
|
60
|
83
|
Intermittent or peak noises may exceed the data given in the table by 5 decibels or more, depending on the source or environment. For many practical problems, however, the data can be considered to be typical source levels at the given distance and condition, or average general activity levels for interiors. The data can be used for design purposes if proper consideration is given to especially loud equipment or sources, which may exceed it, unusual site conditions, and any other conditions that deviate from normal. For example, it is prudent to measure transportation noise at proposed building sites near highways, airports, etc., so design data will represent existing noise sources and reflect specific site features. Note also that modern aircraft, trucks and office equipment may not be as loud as the examples in the table.
Note: Sources for noise level data include Journal of the Acoustical Society of America, Sound and Vibration, Noise Control Engineering Journal and technical publications of the U.S. Environmental Protection Agency and the U.S. National Bureau of Standards.
Reprinted from the 1988 edition of Architectural Acoustics with the kind permission of Author, David Egan.
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