Sound energy is generated by an oscillating, traveling wave which is transmitted through a gas, solid or a liquid. The wave is basically pressure, and is made up of frequencies that are within hearing range and of a sufficiently strong level to be perceived by hearing organs. The vibrations created by the oscillating wave of pressure causes the sensors in the receiving hearing organs to vibrate, and the vibrations are translated into the sounds we hear. Sound energy, therefore, is basically anything that our hearing organs receive, perceive and translate as the sounds we hear. These are many, and there are countless examples in everyday life.

Firstly, there is the sound of the alarm clock that wakes us up. In order to rouse us from a deep slumber, many of us set the alarm to a high volume. The effect of this is for the waves emitted by the clock to cause rapid wave oscillation and high pressure, thus causing the receptors in our hearing organs (the ear drums), to vibrate and transmit the sounds entering the ear canal to the inner ear. As a result, the intense waves generated by the loud alarm clock cause rapid vibrations and, therefore, loud noise.

Similarly, when we step outside, we will be confronted with traffic noise-often a low humming-depending on where you live and the volume of traffic. The lower frequencies transmitted mean more constant, but lower volume sounds. If there are workmen operating nearby with a pneumatic drill, we will again be subjected to the intense vibrations and higher frequencies, resulting in loud noise that will possibly result in physical pain. Another example of the way in which loud noise volume can result in physical pain can be demonstrated by taking a pair of headphones, and plugging them into a stereo or portable music player. If you then turn the volume up high and press the play button, you will be subjected to constant, high pressure sound waves causing incredibly high-speed vibrations that will distort the actual sound heard. When you turn the music off and take the headphones out, you may well experience tinnitus, or ringing in the ears, caused by minor, temporary damage. If you expose yourself to loud noise often, you may find that you experience this ringing constantly. Musicians can find themselves thus afflicted, especially those that play in rock bands.

You can see a physical manifestation of sound energy if you turn the volume up and place a speaker on a hollow surface. The intense wave pressure will cause the surface (or object) to vibrate, and this vibration is another manifestation of sound energy.

Sound energy can also be used for therapeutic purposes and in medicine. Sound vibrations are used in ultrasounds and indicate the presence of tumors or other objects in the human body by bouncing off them and emitting echoes that can chart what is there. Ultrasounds are not perceptible to human hearing, but some animals use similar techniques to navigate in the dark. Bats are a good example, and their ultrasound wave signals bounce off of objects and the returning echoes indicate to them whether or not an object is in the way.

(Energy FAQ Series)

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