# Sound Wave Equations Calculator

## Science Physics Formulas

Solving for Noise Pollution Level NPL in db(A)

#### Inputs:

 dB(A) level exceeded 10 percent of time (L10) decibel
 dB(A) level exceeded 50 percent of time (L50) decibel
 dB(A) level exceeded 90 percent of time (L90) decibel

#### Conversions:

 dB(A) level exceeded 10 percent of time (L10)= 0 = 0decibel
 dB(A) level exceeded 50 percent of time (L50)= 0 = 0decibel
 dB(A) level exceeded 90 percent of time (L90)= 0 = 0decibel

#### Solution:

 noise pollution level NPL in dB(A)= NOT CALCULATED

#### Other Units:

Change Equation
Select to solve for a different unknown
 sound pressure level sound pressure reference pressure sound intensity level sound intensity reference intensity intensity at a distance from point source distance from sound source power emitted wave frequency wave velocity wavelength noise pollution level NPL
Where
 SPL = sound pressure level, decibels (db) P = sound wave pressure, newtons/meter2 Pref = reference pressure or hearing threshold, newton/meter2 IL = intensity level, decibel (db) I = sound intensity, watt I0 = reference intensity or least audible sound level, watts PAV = average power, watt NPL = noise pollution level, decibel (db)

Notes:
- Usually, I0 is set to 10-12 watts
- Usually, Pref is set to 0.00002 newtons/meter2
References - Books:
1) P. Aarne Vesilind, J. Jeffrey Peirce and Ruth F. Weiner. 1994. Environmental Engineering. Butterworth Heinemann. 3rd ed.
2) Tipler, Paul A.. 1995. Physics For Scientists and Engineers. Worth Publishers. 3rd ed.

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