Intensity of Sound
Intensity of Sound
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: Examples of sound intensities
|
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 |
Vuvuzelas feature prominently at soccer events in South Africa. The intensity of the sound from a vuvuzela depends on how close you are. In the table below, 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 |
The table above shows 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
This lesson is part of:
Mechanical Waves and Sound