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Intensity of sound [NOT IN CAPS]

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).

Table 1: Examples of sound intensities.

Source

Intensity (dB)

Times greater than hearing threshold

Rocket Launch

180

1018

Jet Plane

140

1014

Threshold of Pain

120

1012

Rock Band

110

1011

Factory

80

108

City Traffic

70

107

Normal Conversation

60

106

Library

40

104

Whisper

20

102

Threshold of hearing

0

0

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 2 you can see how the intensity differs.

Table 2: 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

Frequency (Hz)

At ear

Bell opening

1 m

2 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

Vuvuzelas in action

Image

Photo by Dundas Football Club on Flickr.com