What is sound pressure?
Sound pressure is the amount of air pressure fluctuation a noise source creates. We “hear” or perceive sound pressure as loudness. Sound pressure also depends on the environment in which the source is located and the listener’s distance from the source. The sound produced by the drum is louder two meters from the drum if it is in a small bathroom, than if it is struck in the middle of a football field. Generally, the farther one moves from the drum, the quieter it sounds. Also if there are hard surfaces that can reflect the sound (e.g. walls in a room), the sound will feel louder than if you heard the same sound, from the same distance, in a wide-open field. Sound pressure is usually expressed in units called pascals (Pa). A healthy, young person can hear sound pressures as low as 0.00002 Pa. A normal conversation produces a sound pressure of 0.02 Pa. A gasoline-powered lawn mower produces about 1 Pa. The sound is painfully loud at levels around 20 Pa. Thus the common sounds we hear ha
