What a racket: Noise factfile

Noise is often described as an unwanted sound.

The loudness of noise is measured in decibels and the scale goes from 0 to around 140 decibels (dB).

Low Frequency sounds are slow vibrations that make a tone of low pitch. Low Frequency sounds include things like the bass beat of music, or the hum sound associated with air condition units.

High Frequency sounds are fast vibrations that make a tone of high pitch.

Here are examples of some typical sounds and their measurements:

140 dB Fireworks/Plane taking off

120 dB Fire engine

100 dB Pneumatic drill

90 dB Disco

85 dB Levels above this may harm our hearing

70 dB Vacuum Cleaner

50 dB Boiling Kettle/Rainfall

40 dB Refrigerator

30 dB Bedroom at night

10 dB Breath

Can everyone hear the same sounds?

No, teenagers and children can hear much higher pitched noises then adults.

Some people have suggested that high pitched noises should be played in some places in order to discourage teenagers from hanging around such as the 'mosquito boxes' put up outside shops to keep away gangs.

But some teenagers used this biological difference to their advantage. By placing high pitched ringtones on their mobile phones, students were able to receive messages and calls without their teachers ever noticing!

World Records

The World's Loudest Burp: performed by British man Paul Hunn at the offices of the Guinness World Records, London, UK, July 20th 2004.

It measured in at 104.9 dB

It was measured from a distance of 2.5m (8ft 2in) and 1m high (3 ft 3 in), and read 104.9 dB on a certified and calibrated class 1 precision measuring noise level meter.

Noisiest beasts!

The world's noisiest land animals are the howling monkeys (ALOUATTA) of central and South America. The males have an enlarged bony structure at the top of the windpipe, which enables the sound to reverberate, and the fearsome screams have been described as a cross between the bark of a dog and the bray of an ass increased a thousandfold. Once in full voice they can be heard clearly up to 16 km/ 10 miles.

The low - frequency pulses made by BLUE WHALES when communicating with each other have been measured up to 188 decibels, making it the loudest sound emitted by any living source. They have been detected 850 km/ 530 miles away.

Music - a form of interrogation?

Since 2002 music has been used as an interrogation technique by the CIA.

An escaped prisoners from one CIA prison in Afghanistan said: "They would not let you rest, day or night.

Stand up, sit down, stand up, sit down. Don't sleep. Don't lie on the floor."

The detainees were also forced to listen to rap artist Eminem's "Slim Shady" album. The music was so foreign to them it made them frantic, sources said.

When contacted after the completion of the investigation, CIA officials would neither confirm nor deny the accounts. They simply declined to comment.

What's the loudest noise you've ever heard? What sounds drive you mad? Post your comments below.