## Step6

Volume

Study the text and do the assignment below.

Decibel The loudness of sound -also called volume- is measured in decibel (dB). A classroom with a murmur produces about 50 dB, a disco often more than 100 dB. Sounds louder than 80 dB damage your hearing. If you listen to loud noise for a longer period of time the damage increases. This is because every time you listen to a sound which is too loud, sensory cells in the cochlea die. Each time a sensory cell dies, you lose a bit of hearing. Playing loud music through earphones can be damaging to your ears. Because your ears get damaged from listening to loud sounds for too long, employers need to make sure there isn't enough noise at the workplace. If there is too much noise they have to make employees wear hearing protection. Every 3 dB above 80 dB halves the time you should be exposed to the sound.
Volume (in dB) | Maximum time
80 | 8 hours
83 | 4 hours
86 | 2 hours
100 | 5 minutes
110 | 30 seconds
The sofstest sound humans can hear is 3 decibel. This 'softest' sound is called the absolute threshold of hearing. The volume of sound can be measured with a decibelmeter. Your smartphone should have a free app in the app store which works as a (not very accurate) decibelmeter. The volume of a vacuum cleaner is around 70 dB. If two vacuum cleaners make twice as much noise, you might expect the volume to be 140 dB. However, this isn't true. When a sound is twice as loud, it is only 3 dB louder. So if one vacuum cleaner produces a volume 70 dB, two vacuum cleaners produce a volume of 73 dB. Remember: When the sound is twice as loud, the volume is 3 dB louder.