Noise Dosimeter

The data-logging* Dosimeter enables you to make calibrated noise dose measurements using standard dosimeter options. The dosimeter displays the current dose, projected dose, and 8-hour time-weighted average sound level (TWA).

The noise dose is a percentage of a maximum permissible daily noise exposure, where the maximum exposure is generally specified as the equivalent to being exposed to some constant sound level, such as 90 dBA, over a specific period of time, such as a typical 8-hour work day.

The projected dose offers an estimate of the total 8-hour dose, based on the current dose and elapsed time.

When data logging is enabled, a data log graph will be available in the Dosimeter tool screen. You can switch between the main Dosimeter display and the data log graph by tapping the page control or by swiping back and forth with a single finger. Data can be logged as often as every 0.1 seconds for up to 8 hours, every second for up to 72 hours, or every 10 seconds for up to two weeks.

Logged data includes Dose, Projected Dose, LpAS (A-weighted, slow response), and TWA.

A calibrated microphone is required in order to make accurate measurements.

• Criterion Sound Level
  The criterion sound level is the average, A-weighted sound level over an 8-hour period that determines the maximum permitted daily noise exposure (100% noise dose). The dosimeter supports commonly-used criterion levels of 80, 85, and 90 dB.
• Threshold Sound Level
  The dosimeter allows you to select a sound level below which the current sound input makes no contribution to the noise dose. In other words, the dosimeter only includes input sound levels above the selected threshold level. Threshold levels from 40 to 90 dB are supported in 10 dB increments.
• Exchange Rate
  The exchange rate specifies a relationship between a change in sound level and a corresponding change in noise exposure duration (by a factor of 2) to maintain a constant measure of noise dose. A 3dB exchange rate is referred to as an equal energy exchange rate, because the equivalent acoustic energy is preserved when a sound level reduction of 3dB is accompanied by a doubling of exposure duration (or when a sound level increase of 3dB is accompanied by a halving of exposure duration).