Enter the total sound level in decibels and the total time of exposure into the calculator to determine the total weight average (TWA) noise exposure.

## TWA Formula

The following formula is used to calculate the total weight average noise exposure.

TWA = 16.61 * log10* (D/100) + 90

D = 100 * (C / ( 2 ^ ( L-90)/5 ) )

• Where TWA is the total weight average noise exposure rating
• C is the total time of exposure
• L is the total A-weight sound level (decibels)

* Note this calculation assumes the sound level is constant for the entire duration of the day.

## TWA Definition

What is TWA?

TWA stands for total weighted average. This term is most often used in OSHA regulations to denote a total weighted average of sound exposure.

This value is used to determine the risk associated with a loud work environment.

## Example Problem

How to calculate TWA?

1. First, determine the total time of exposure.

For this example, we will use a standard 8 hour workday as the time exposure.

2. Next, determine the A-weighted sound level.

For this problem, the A-weighted sound level is found to be 82 decibels.

3. Finally, calculate the TWA.

Using the formula above, the TWA is calculated to be:
TWA = 16.61 * log(10) * (D/100) + 90
D = 100 * (8 / ( 2 ^ ( 82-90)/5 ) )
TWA = 113