The value of acoustic pressure in pascals

Professional Definition

The value of acoustic pressure in pascals (Pa) is the root mean square (RMS) deviation of pressure in a medium (e.g., air) from the average atmospheric pressure, caused by an acoustic wave.

In the physics of sound, pascal is the basic unit of measurement for wave amplitude. Since the range of audible pressures is vast (from 0.00002 Pa to over 200 Pa), in engineering practice, a logarithmic scale (decibels) is used; however, the value in pascals directly reflects the mechanical energy of the wave acting on the surface.

Acoustics in Simple Words

Imagine a sheet of a lake. The depth of water is a constant atmospheric pressure that presses down on us with tremendous force (about 100,000 Pa), but we do not feel it because it is constant. Sound is small ripples on the surface of that lake. The value of acoustic pressure in pascals tells us how high those ripples are. Interestingly, our ears are so sensitive that they can detect a "wave" with a height of just a fraction of an atom's thickness, corresponding to micropascals, while a departing jet generates "waves" with a pressure on the order of hundreds of pascals.

Summary

Pascal (Pa) is the physical unit of measurement for acoustic pressure, describing the actual force of a sound wave. It is a linear quantity that is converted to a more convenient logarithmic scale expressed in decibels (dB SPL).