Sound

Sound

Sound is produced by the vibrations of an object or mechanism and transmitted in the form of waves—alternating increase and decrease in pressures. It radiates outward through a material medium of molecules, more or less like the ripples spreading out on water after some he7vy object has been thrown into it. The frequency of sound is determined by the number of times the vibrating waves undulate per second. The Slower the cycle, the lower the pitch.

Alifye - Theory of Space - Sound

Ultra Sonics

The human ear cannot generally hear sounds frequencies higher than 20,000 vibrations per second or 20,000 1-1Z., Sounds of frequencies higher than 20.000 HZ which are inaudible are called ultra – sonic. Bats produce very high sound when they fly they are at ultra – sonic frequencies from 20 000 to 100.000 cannot hear them.

Speed of Sound

The speed of sound varies according to the nature of the carrier media. The speed of sound is around 1088 feet per second. In water, sound travels about 5 times faster than in air. In iron and steel, it is even faster, about 3 times faster than the speed in water.

Speed of sound through some media is:
Ice — cold water        4938 ft per second
Brick                          11960 ft per second
Granite                      1296 ft. per second
Hardwood                 12620 ft. per second
Glass                         16410 to 19690 ft per second

Alifye - Speed of Sound - Super Sonic - Theory of Space

Super - Sonic

Super — sonic speed is greater than the speed of sound i.e 760 miles per hour. This is a unit, worked out by Ernst Mach and therefore named after him. Mach is the ratio of the speed of flight to the speed of sound under the same conditions of pressure and density. When a plane moves at the speed of sound, it is Mach I. When a plane move at twice the speed of sound (supersonic), it is Mach2. When it is less than the speed of sound it is sub — sonic and therefore lesser than Mach I. At half the speed of sound it is Mach '/2.

Sound Barrier

It is the point at which the speed of the flight equals the speed of sound. When a plane flies faster than sound. it is said to cross the sound barrier.

Sonic Booms

When a plane passes the sound barrier, speed produces shock waves in the atmosphere which produce booms like thunder clips. These are called sonic booms. They trouble the ears of the people of the areas over which the aircraft is flying at supersonic speed. But these do not trouble the passengers inside the aircraft because it is flying faster than the shock waves learning them behind.

Decibel

The loudness of the. sound. reflects the pressure of the sound waves. This pressure is expressed in decibels. A decibel may be regarded as the smallest difference between sounds detectable by the human ear. Th. e human ear can safely respond to pressures up to 120 decibels. Any intensity higher than this is painful, and can conceivably damage the delicate nerves of the ear.