Leq refers to the value given to the level of sound that varies over a period of time. In essence, leq represents the average sound level that is recorded for a specific time period. The level of sound is expected to fluctuate at a particular place or space and it can only be measured by capturing bits of information at different parts of a particular sample to get a more accurate sound reading. For most people that measure sound and noise, the preferred reading is through the use of leq measurement. Measurement of sound through leq is said to capture the true continuous sound level of a particular space including all the fluctuations that occur in between.

Sound or noise is typically measured in decibels. Louder sounds are recorded with higher decibels while lower sound values also correspond to low decibel levels. The problem with mere decibel recording is that it only captures how noisy or quiet a particular space is at a specific point in time. Fluctuations in noise are not taken into account when recording the highest or lowest decibel level for a particular space. For rooms with sound levels that continuously fluctuate for any given day, the sound level average must be recorded instead of the standard decibel reading. This is where the leq measurement comes in and it is also reported in decibel values. This sound measurement method is particularly useful in determining the overall sound or noise value for a given space at a designated period of time.

The noise level in one classroom for example can best be interpreted using leq measurement. For a 24-hour period, the noise level at this particular classroom is expected to fluctuate from very high decibels when there are classes going on in the morning, to very low decibels when the students are all outside of the classroom and preparing to go home. To get the true value of the sound level of the class room, averaging of decibels should be done and this is recorded through leq values.