period one
Fundamentals of Sound
notes
Sound Power and Sound Pressure
ISound power
KAcoustical energy emitted by the sound source
KUnaffected by the environment
ISound pressure
K Pressure disturbance in the atmosphere
K Affected by strength of source, surroundings, and distance between source and receiver
Figure 11
Sound Power and Sound Pressure
Sound power and sound pressure are two distinct and commonly confused characteristics of sound. Both are generally described using the term decibel (dB), and the term “sound level” is commonly substituted for each. To understand how to measure and specify sound, however, one must first understand the difference between these two properties.
Sound power is the acoustical energy emitted by the sound source, and is expressed in terms of watts (W). It is not affected by the environment.
Sound pressure is a pressure disturbance in the atmosphere, expressed in terms of pascals (Pa), that can be measured directly. Sound pressure magnitude is influenced not only by the strength of the source, but also by the surroundings and the distance from the source to the listener. Sound pressure is what our ears hear and what sound meters measure.
While
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