Noise exposure dose

Choose the criterion before comparing results

The NIOSH option uses an 85 dBA, eight-hour reference and a 3 dB exchange rate. OSHA options use a different basis and threshold treatment. Results calculated under different criteria are not interchangeable. Enter representative measured levels and durations, not a machine's maximum advertised sound level.

Dose is not a complete hearing-risk assessment

The worksheet does not measure exposure, account for hearing-protector fit, or fully assess impulsive noise. Use suitable monitoring and the requirements that apply to the workplace. A dose below a selected reference is not a promise that an exposure cannot harm hearing.

Adding exposures on the same criterion

For each noise period, divide its duration by the reference duration associated with that sound level under the selected criterion. A period that uses half its reference duration contributes 50 percent dose. Another period contributing 25 percent brings the modeled total to 75 percent. Do not average those percentages or divide the sum by the number of periods.

Exchange rate determines how reference duration changes as sound level rises, so different criteria can assign different doses to the same measured day. Threshold settings also affect which exposures are counted. Keep the selected criterion consistent when comparing scenarios or monitoring records. Use time-weighted measurements or representative periods appropriate to the assessment; a brief maximum reading does not describe an entire shift. The calculator cannot establish microphone calibration, measurement position, or whether the recorded periods capture the actual exposure. It also does not convert a protector's labeled rating directly into a reliable protected dose. Workplace assessment and hearing-protection decisions require appropriate measurement and application-specific guidance.

Formula

Dose = 100 Σ(Cᵢ / Tᵢ); Tᵢ = 8 × 2^((criterion − level)/exchange). NIOSH uses 85/3 with 80 dBA threshold; OSHA uses 90/5.