Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Sound - Ldn - Day and Night Level

The EPA A-weighted sound level day and night equivalent definition - Ldn - for a 24 hour period.

Sponsored Links

The Environmental Protection Agency - EPA - has adopted a system of four "sound descriptors"

to summarize how sound is heard and measured and to determine the impact of noise on health and welfare.

Day-Night Sound Level - Ldn

is the A-weighted equivalent sound level for a 24 hour period with an additional 10 dB imposed on the equivalent sound levels for night time hours of 10 pm (22) to 7 am (07).

Day-Night Sound Level can be expressed as

Ldn = 10 log (1 / 24 (15 (10Ld/10) + 9 (10((Ln + 10)/10)))                            (1)

where

Ldn = day-night sound level (dBA)

Ld = daytime equivalent sound level (dBA)

Ln = nighttime equivalent sound level (dBA)

Examples of typical outdoor Day-Night Average Sound at various locations:

Typical Day and Night Sound Level vs. Location
LocationLdn (dBA)
Apartment next to freeway 87
3/4 mile from runway at major airport 86
Downtown with construction activity 79
Old urban residential area 59
Wooded residential 52
Agricultural crop land 44
Rural residential 39
Wilderness ambient 35

Example - Day-Night Sound Level

The equivalent daytime sound level is 70 dB and the equivalent nighttime sound level is 50 dB. The Day-Night sound level can be calculated as

Ldn = 10 log (1 / 24 (15 (10(70 dB)/10) + 9 (10((50 dB)+ 10)/10))

      = 68.2 dB

Day-Night Sound Level Calculator

Use the calculator below to calculate EPA 24 hour Day-Night sound level.

Sponsored Links

Related Topics

  • Acoustics

    Room acoustics and acoustic properties, decibel A, B and C, Noise Rating (NR) curves, sound transmission, sound pressure, sound intensity and sound attenuation.

Related Documents

Sponsored Links

Search

Search is the most efficient way to navigate the Engineering ToolBox.

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with older versions of the amazing SketchUp Make and the newer "up to date" SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp Make/Pro from the Extension Warehouse !

Translate this Page

Translate this page to Your Own Language .

About the Engineering ToolBox!

Privacy Policy

We don't collect information from our users. More about

Citation

This page can be cited as

  • The Engineering ToolBox (2004). Sound - Ldn - Day and Night Level. [online] Available at: https://www.engineeringtoolbox.com/sound-level-d_719.html [Accessed Day Month Year].

Modify the access date according your visit.

3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Unit Converter

















































2.27.11

Sponsored Links
.