Sound Pressure

When the radiated sound power is confined to pass through a smaller unit area, the resultant sound intensity increase produces an increase in the sound pressure at each point over the surface area. The sound pressure in Pascals, at any point on the sphere, can be expressed as a sound pressure level in decibels. So, the sound intensity produces a sound pressure level at each point on the surface area. A sound level meter measures sound pressure, and converts it to sound pressure level using the formula shown.

The sound pressure level is usually the quantity of interest in sound system design.