Lewis L. Spence
Sound is the form of energy which allows us to hear and communicate through speech. It is responsible for acquainting us with our environment through the remarkable organ called the ear. Like light and some other forms of energy, sound travels in the form of waves. They all have energy and their waves can be reflected, refracted, diffracted or absorbed. One of the other common properties of waves is that they transmit energy and information through a medium but the medium itself is not moving with the wave. The disturbance occurs in the medium and is passed on from one point to the next. In the case of sound waves, the disturbance is in the form of a change in pressure and density which is sometimes described as a vibration in the medium.
Light waves and radio waves travel at a speed of 3 x 10 meters (186,000 miles) per second, while sound waves travel at 344 meters (1100 ft) per second at 70 F. Unlike the other mentioned waves, sound waves do not travel in a vacuum; they require a material medium in the form of a solid, liquid or gas. In water sound will travel at a speed of about 1500 meters per second (5000 ft/sec), which is about five times its speed in air. While in a steel material the speed could be more than three times faster than in water.
