Zyra's site //// CONCEPTS //// SCIENCE //// SITE INDEXPicture a sound?

deciBels Explained

Decibels are commonly believed to be just a measurement of how loud a sound is. But there's more to it than that, because they are convenient way of dealing with scientific phenomena that worth logarithmically. Things like signal-to-noise ratio for example. Logarithms - classic oldfashioned conjuring trick for doing hard sums like magic (link here to see how the conjuring trick is done), are also a way in which some things in nature work, like sound for example.

deciBels (dB) in sound:

Approximate descriptions of levels of sound

0 dB Threshold of hearing
10 dB Rustling of leaves
20 dB Whisper
30 dB Quiet conversation
40 dB Average home
50 dB Normal conversation
60 dB Busy shop
70 dB City street
80 dB Busy workplace
90 dB Underground railway
100 dB Pneumatic drill 10ft away
110 dB Propeller aircraft taking off
120 dB Jet aircraft taking off

What's interesting here is that each 10dB added makes the sound TEN TIMES as loud. So, 90dB is quite loud, but 100dB is ten times louder, and 110dB is 100 times louder, etc.

What's really good about this is that it's possible to put things on a scale which is understandable even though the ratios between them are very large.

If you found this page useful, see [response]