Sound is a mechanical wave that is an oscillation of pressure
transmitted through a solid, liquid, or gas, composed of frequencies.
Sound can’t travel through a vacuum (an area empty of matter).
The scientific study of sound waves is known as acoustics.
The sound of thunder is produced by rapidly heated air surrounding lightning which expands faster than the speed of sound.
The loudest natural sounds ever made on Earth are probably gigantic volcanic eruptions , such as the explosions of the island of Krakatoa.
Some of the loudest sounds produced by our own invention are the
noise of space rockets blasting from the launch pad. The biggest were
the Saturn V rockets that launched the USA’s Apollo moon missions of
1968-72. They had their greatest success when Apollo 11 landed on the
Moon – an airless and therefore completely silent place – on 20 July
1969. Once a space rocket had taken off and entered the vaccum of space,
it became totally silent.
One musical piece has no sound at all. It is called 4 minutes 33
seconds. It was ‘ written ‘ by the American composer John Cage in 1954. A
pianist sits at the piano and plays nothing for exactly 4 minutes and
33 seconds. The content of the composition is meant to be perceived as
the sounds of the environment that the listeners hear while it is
performed, rather than merely as four minutes and thirty three seconds
of silence.
Middle C , with a frequency of 256 Hertz,is near the top of the
singing range of a typical adult male voice. It is also near the lower
end of the singing range of an adult female voice.
In the deep ocean . the sperm whale uses sound to stun or kill its
prey. Its sends out giant grunts, immensely powerful bursts of sound
that can disable nearby fish, squid and other victims.
Huge cathedrals, with their hard walls and floors of stone, glass
and wood, are amazing places for acoustics. Almost any sound seems loud
and long, a sit echoes and reverberates through the surfaces. This is
why church singing sounds so special.
In the recording studio any
stray sound is a nuisance. So the walls, ceilings and floors are covered
with sound-absorbing substances, such as wavy-surfaced tiles and thick
carpets. There is a continuing search for ‘acoustically dead’ materials
that absorb all sounds.
