Sound level meters measure at discrete times, while dosimeters measure continually over time for a more accurate estimate of risk.
|LED||Dose %||Risk Factor|
|green (slow flash)||< 25%||No risk of hearing loss|
|green (fast flash)||25%||No risk of hearing loss|
|green||50%||1/2 daily dose reached|
|yellow||100%||Limit of permissible exposure|
|red||200%||2x allowable daily dose|
|red||400%||4x allowable daily dose|
|red||1600%||16x allowable daily dose|
|red||3200%||32x allowable daily dose|
Daily noise dose is determined by both the intensity of the sound and the amount of exposure time. A 100% dose means that a person has reached the maximum noise exposure for the day, and continued exposure to loud sound could lead to hearing loss. Ideally, hearing protection should be used before the dose reaches 100% since dose limits are based on averages, and some ears are more susceptible to noise damage than others. When the noise dose exceeds 50% a person has reached half the maximum noise exposure for the day and it’s a good idea to use hearing protection to prevent over-exposure, particularly if a 50% dose reading is reached early in the day.
In cases of gunfire and other impulse noise, no conventional dosimeter measures the risk accurately. More specialized equipment is required to measure impulse noise.