Steve's Digicams suggests measuring the sound intensity of a room using a sound pressure level meter with a sensitivity ranging from 55 to 120 decibels. If measuring sound intensity for the purpose of placing speakers, it is important to set up the meter in the part of the room where people are most likely to be while listening. It is recommended that the listening position be centered between the speakers being tested.
When testing the sound intensity of a room, it is necessary to use a tone test audio recording that allows the sound pressure level meter to be calibrated to a particular tone. Sound intensity is a measure of sound pressure per unit area and is commonly represented in watts. Sound pressure, on the other hand, is measured in decibels. There are two broad categories of sound level meters available, ones that take an instantaneous recording of sound levels and ones that take measurements of sound levels at intervals in order to arrive at average sound levels over time.
Decibels are a logarithmic unit that is more appropriate for measuring the range of sound intensity that is relevant to human hearing because humans interpret sound pressure input in a logarithmic way. The sound of leaves rustling outside is approximately 10 decibels, while the sound of intense traffic noise is about 70 decibels. At 85 decibels hearing loss can occur if exposed for 8 hours or more, and hearing loss can occur after 15 minutes if exposed to sound of 100 decibels or more.