140
WILLIAM N. TAVOLGA
Table I
Comparative Chart of Approximate Acoustic Pressure Levels of Common
Sounds in Air and in Watera
Acoustic
pressure
Sounds in air
(dB)
Sounds in water
Jet aircraft takeoff (at 75 meters)
Threshold for human aural discomfort
(discomfort at 1000 Hz)
Loud auto horn (at 1 meter)
Small propeller aircraft. (at 5 meters)
New York subway train (at 10 meters)
Noisy business office
Home high fidelity set
Average conversation (at 1 meter)
Private business office
Average residence
Quiet country residence
Quiet whisper
Human hearing threshold (at 1000 Ha)
60
50
40
30
20
10
0
- 10
- 20
-30
- 40
- 50
- 60
-70
- 80
Underwater dynamite explosion (at
25 hp outboard motor (at 15 meters)
Toadfish boat-whistle sound (at 1
Rough sea (state 6 )
Large chorus of marine catfish
Noise of ships in busy harbor
Large chorus of snapping shrimp (at
Calm sea (state 0)
Squirrelfish hearing threshold (at
100 meters)
meter)
100 meters)
800 Hz)
Threshold of hearing of ostariophysine fishes
a The reference point is set a t 0 dB = 1 pb (= 1 dyne/cm2). To convert to a reference
Ambient noise in the sea normally includes the sounds produced by
wave motion on the surface, friction of moving water currents against
the bottom and against each other, the noise of shipping traffic, and,
superimposed on all that, the noises of marine animals (Wenz, 1962,
1964) (Fig. 2). The average level of ambient sea noise is about 10 or
15 dB pb.
In air, sound is usually defined as a more or less periodic form of compression waves that can be detected by the human ear. The frequency
range, again with reference to human hearing, is normally considered to
be from 20 to 20,0000 Hz. At 20 Hz, the sound is “felt” rather than heard,
and most people cannot detect sounds above about 16,000 Hz ( = 16
kHz). This is a subjective and anthropomorphic definition of sound and
does not apply to acoustic energy in water. Since water is highly resistant
to compression, the propagation of sound in water usually involves particle displacement as well as compression. This displacement is particpoint of 0.0002 pb add 74 dB.
WILLIAM N. TAVOLGA
Table I
Comparative Chart of Approximate Acoustic Pressure Levels of Common
Sounds in Air and in Watera
Acoustic
pressure
Sounds in air
(dB)
Sounds in water
Jet aircraft takeoff (at 75 meters)
Threshold for human aural discomfort
(discomfort at 1000 Hz)
Loud auto horn (at 1 meter)
Small propeller aircraft. (at 5 meters)
New York subway train (at 10 meters)
Noisy business office
Home high fidelity set
Average conversation (at 1 meter)
Private business office
Average residence
Quiet country residence
Quiet whisper
Human hearing threshold (at 1000 Ha)
60
50
40
30
20
10
0
- 10
- 20
-30
- 40
- 50
- 60
-70
- 80
Underwater dynamite explosion (at
25 hp outboard motor (at 15 meters)
Toadfish boat-whistle sound (at 1
Rough sea (state 6 )
Large chorus of marine catfish
Noise of ships in busy harbor
Large chorus of snapping shrimp (at
Calm sea (state 0)
Squirrelfish hearing threshold (at
100 meters)
meter)
100 meters)
800 Hz)
Threshold of hearing of ostariophysine fishes
a The reference point is set a t 0 dB = 1 pb (= 1 dyne/cm2). To convert to a reference
Ambient noise in the sea normally includes the sounds produced by
wave motion on the surface, friction of moving water currents against
the bottom and against each other, the noise of shipping traffic, and,
superimposed on all that, the noises of marine animals (Wenz, 1962,
1964) (Fig. 2). The average level of ambient sea noise is about 10 or
15 dB pb.
In air, sound is usually defined as a more or less periodic form of compression waves that can be detected by the human ear. The frequency
range, again with reference to human hearing, is normally considered to
be from 20 to 20,0000 Hz. At 20 Hz, the sound is “felt” rather than heard,
and most people cannot detect sounds above about 16,000 Hz ( = 16
kHz). This is a subjective and anthropomorphic definition of sound and
does not apply to acoustic energy in water. Since water is highly resistant
to compression, the propagation of sound in water usually involves particle displacement as well as compression. This displacement is particpoint of 0.0002 pb add 74 dB.