Sound#Sound pressure level

The sound is a colloquially shortened term for the level of acoustic size, which is usually given in the auxiliary decibels. One of the following sizes can refer to:

• Mostly it will be the sound pressure level Lp as sound field size, at a specific location describes the action of sound ( noise immission ) and strongly influenced by the type of environment ( for example in a room or outdoors, distance to a sound source ) depends on rare
• The sound power level LW, the strength of a sound source describes ( acoustic emission ) and does not depend on the type of environment, but the characteristics of the sound source.
• The sound intensity level LI, of the logarithmic ratio of the sound intensity I1 in a sound field to the reference value I0 (DIN 45630 ) as sound energy quantity describes.

As the sound pressure level as sound field quantity, so the sound intensity level is as sound energy size of location and environment dependent and direction-dependent.

For the interpretation of a given " noise level " must not only be known in the rule, which is meant these sizes, but are often more input is required, as the measurement protocol used, the corresponding frequency or time evaluation or the location of a measurement and its properties.