how sound effing works! LOL.
Sound is a vibration or wave of air molecules caused by the motion of an object. The wave is a compression wave where the density of the molecules is higher. This wave travels through the air at a speed dependent on the temperature. A sound wave contains energy, which in turn means it can make things move. However, if the wave strikes something solid, the wave will bounce back -- an echo. Sound energy can be changed into other forms of energy, e.g. electrical energy, and vice versa; this is one of its properties that allow us to communicate by telephone.
Sound is produced when an object moves or vibrates. Without movement there could be no sound. When an object moves or vibrates, the air molecules around the object also vibrate. Vibrating objects (as long as they are not in a vacuum) produce sound.
Sound travels at different rates in different media. In dry air, sound travels at 331.6 m/sec at 0 C.
Each molecule moves back and forwards only a tiny distance, but it is enough to cause the air particles to bump into each other. This creates areas where there are many molecules pushed close together --compression; and areas where molecules are spread far apart --rarefactions. These compressions and rarefactions move outwards away from the sound source in circles. A sound wave is created when a series of these pressure changes/waves move through the air.
What is the frequency of sound waves?
When we draw a sound wave, the wave peaks and valleys are close together or far apart. Sound waves vibrate at different rates or "frequencies" as they move through the air. Frequency is measured in cycles per second, or Hertz, after the German physicist who experimented with sound in the 19th century. The faster an object vibrates, i.e. the higher the frequency, then the higher the pitch of the sound. For example, a tuning fork for A above middle C will vibrate 440 times per second and has a frequency of 440 Hertz.
What is the wavelength of a sound wave?
When a wave is created, the distance between one compression and the next compression is called the wavelength. The faster the sound waves pass a given point, the shorter the wavelength and the higher the frequency. Sounds of all frequencies travel at the same rate in the same medium. (Sound in dry air at 0 C travels at the rate of 1200 kilometres per hour, or 331.6 m/sec; in a solid medium the sound waves travel faster.)
What is the amplitude of sound waves?
The vibrations can also "squeeze" the air molecules together very hard or very gently. This squeezing is called "amplitude" and is represented on the top half of the diagram below. The bottom half of the diagram is a representation of the pressure of the air during a sound wave. The horizontal line represents normal air pressure.
The more we push an object to make it vibrate, the larger the vibrations and the louder the sound, or the greater the amplitude. Sound waves with the same frequency can have different amplitudes.
Can sound energy be changed into other forms of energy?
Since sound is a form of energy, it can be changed from one form to another. Other forms of energy can be transformed into sound. Sound energy can be changed into electrical energy. Sound waves that are changed into electricity can be seen on an oscilloscope.
An oscilloscope is a machine that provides a visual record of the voltages of an electrical signal. Connecting a microphone output to an oscilloscope allows us to see the characteristics of a sound wave on a screen.
How can we use the conversion of sound energy?
Technology enables us to "connect" with other people who are not in the room with us. The telephone converts sound energy into electrical energy, and back into sound energy again. It was invented in 1876 by Alexander Graham Bell, a teacher of the deaf.
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