Sound - Ls - Exposure Level

The EPA Sound Exposure Level - Ls - describes the noise from a variable source. It measures the sound change from moment to moment by accumulating intensity and exposure duration to measure the total sound energy.

Sound Exposure Level - Ls

The Sound Exposure Level - Ls - is one of the Environmental Protection Agency (EPA) sound descriptors used to describe noise from variable sources such as airplanes, trains, trucks, etc.

Overview

The EPA has adopted a system of four sound descriptors:

  • A-weighted sound level
  • Sound Exposure Level - Ls
  • Equivalent Sound Level - Leq
  • Day-Night Sound Level - Ldn

Measurement

The Sound Exposure Level - Ls measures the sound change from moment to moment with variable sound by:

  • Measuring the maximum sound level
  • Recording the length of time with sound level greater than certain sound pressure levels
  • Accumulating intensity and exposure duration to calculate total sound energy

This metric is particularly useful for assessing noise from moving sources and determining the impact of noise on health and welfare.

Sound SourceTypical Ls Value (dB)Exposure Duration (seconds)Peak Sound Level (dB)
Jet Aircraft Flyover14010150
Helicopter13015145
Train Passby1208135
Truck Passby1105125
Car Passby1003115