Day-Night Average Sound Level (DNL)

DNL sums the individual noise events and averages the resulting level over a 24 hour period. It also includes a 10-decibel adjustment added to those noise events that take place between 10 p.m. and 7 a.m. the following morning. This 10-decibel “penalty” represents the added intrusiveness of sounds that occur during normal sleeping hours.

Although DNL provides a single measure of overall noise impact, it does not provide specific information on the number of noise events or the individual sound levels that occur during the day.

Sound Exposure Level (SEL)
The sound exposure level (SEL) is a composite metric that represents both the intensity of a sound and its duration. The SEL is a logarithmic* measure of the total acoustic energy transmitted to the listener during the fly over event. SEL is the best metric to consider speech interference, noise related awakenings and can create significant and very uncomfortable reactions with impacted citizens when flight reach high sound levels that can exceed 117 dB such as in the case of the Super Hornet.

* See Real Difference in Sound Intensities" under Noise Explained Section” For Logarithmic explanation