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Intensity Of Sound [Not In Caps]

10.4 Intensity of sound [NOT IN CAPS] (ESADE)

Intensity is one indicator of amplitude. Intensity is the energy transmitted over a unit of area each second.

The unit of intensity is the decibel (symbol: dB).

Source

Intensity (dB)

Times greater than hearing threshold

Rocket Launch

180

\(\text{10}^{\text{18}}\)

Jet Plane

140

\(\text{10}^{\text{14}}\)

Threshold of Pain

120

\(\text{10}^{\text{12}}\)

Rock Band

110

\(\text{10}^{\text{11}}\)

Factory

80

\(\text{10}^{\text{8}}\)

City Traffic

70

\(\text{10}^{\text{7}}\)

Normal Conversation

60

\(\text{10}^{\text{6}}\)

Library

40

\(\text{10}^{\text{4}}\)

Whisper

20

\(\text{10}^{\text{2}}\)

Threshold of hearing

0

0

Table 10.3: Examples of sound intensities.

Vuvuzelas feature prominently at soccer events in South Africa. The intensity of the sound from a vuvuzela depends on how close you are. In Table 10.4 you can see how the intensity differs.

Frequency (Hz)

At ear

Bell opening

\(\text{1}\) \(\text{m}\)

\(\text{2}\) \(\text{m}\)

125

36

62

38

35

250

92

106

82

85

500

103

121

102

101

1 000

106

122

108

100

2 000

101

122

110

101

4 000

97

109

110

102

5 000

93

111

109

100

8 000

87

110

107

98

Table 10.4: Average vuvuzela intensity measurements across frequencies at 4 distinct distances from the bell end of the vuvuzela (dBA) taken from South African Medical Journal (Cape Town, South Africa) 100 (4): 192

Vuvuzelas in action