Estimating Hourly Leq from 24 Hour Leq


  • Miranda Lynn Daly Hatch Ltd.
  • Tim Kelsall Hatch Ltd.<br />
  • Hicham Khelladi Hatch Ltd.


The Average Annual Daily Traffic (AADT) for a given area can be used to determine 24 Hour Leq equivalent sound levels near roadways and in the community. This does not give an indication of how the L­eq­ changes through the day. Many jurisdictions, like Ontario use Leq1h as a common descriptor. During a recent project, measurements were taken in residential communities, including next to highways and commuter rail lines and the differences from the 24 Hour L­eq­ were calculated for hourly Leq throughout the day. When averaged, these values can be used as correction factors to help to approximate hourly Leq values ­based on an Leq,24h calculated from AADT data.

Author Biographies

Miranda Lynn Daly, Hatch Ltd.

Noise and Vibration

Tim Kelsall, Hatch Ltd.<br />

Director of Noise and Vibration

Hicham Khelladi, Hatch Ltd.

Noise and Vibration



How to Cite

Daly ML, Kelsall T, Khelladi H. Estimating Hourly Leq from 24 Hour Leq. Canadian Acoustics [Internet]. 2017 Aug. 25 [cited 2023 Mar. 28];45(3). Available from:



Proceedings of the Acoustics Week in Canada