The noise exposure calculator and the decibel calculator both work with sound, but one is arithmetic about time and dose while the other is arithmetic about ratios and levels. The noise exposure calculator totals occupational noise dose under one selected criterion — OSHA or NIOSH — from levels in dB and durations in hours. The decibel calculator converts dB to power or amplitude ratios, converts ratios back to dB, and combines two sound levels logarithmically. The noise exposure page describes the decibel calculator as the tool for logarithmic sound arithmetic; the decibel page describes the noise exposure calculator as the tool when time and workplace limits matter.
What each calculator does
The noise exposure calculator takes one criterion (OSHA or NIOSH), one, two, or three exposures, each with a level in dB (70 to 140) and a duration in hours (0.1 to 24). The allowed time at level L is 8 × 2^−(L−90)/5 under OSHA and 8 × 2^−(L−85)/3 under NIOSH, and each exposure contributes 100 × duration ÷ allowed time. Contributions are summed, and the result also reports criterion time at the highest entered level. The starting case — one 85 dB exposure lasting 8 hours — shows 50.0% dose with 16.00 hours criterion time under OSHA, versus 100.0% with 8.00 hours under NIOSH.
The decibel calculator has three modes. In dB to ratio mode it converts a decibel value to a power or intensity ratio using 10^(L/10), or an amplitude or pressure ratio using 10^(L/20). In ratio to dB mode it applies the same multipliers in the opposite direction, requiring a positive ratio. In combine mode it treats both entries as sound levels and computes L = 10·log10(10^(L1/10) + 10^(L2/10)) — for example, 65 dB and 68 dB combine to 69.76 dB, only 1.76 dB above the louder source. Decibel entries must be finite and between −200 and 200; results round to two decimals.
Side-by-side
| Noise exposure calculator | Decibel calculator | |
|---|---|---|
| Question answered | What is the dose percentage for these exposures under one criterion? | What is the ratio or combined level for these decibel values? |
| Inputs | Criterion, 1–3 levels (70–140 dB) and durations (0.1–24 h) | Mode, decibel value(s) or ratio, and power/amplitude choice |
| Core math | dose = Σ 100 × duration ÷ T, with T = 8 × 2^−(L−90)/5 or 8 × 2^−(L−85)/3 | L = 10·log10(ratio) or 20·log10(ratio); combine via logarithmic addition |
| Output | Dose percentage (one decimal) plus criterion time | dB, ratio, or combined level (two decimals) |
| Criterion | OSHA 90 dB/5 dB exchange or NIOSH 85 dB/3 dB exchange | None — generic dB arithmetic, no weighting |
| Regulatory role | Dose must be labeled with its standard | Not a substitute for calibrated noise assessment |
When to use which
Use the noise exposure calculator when the question is occupational dose: how much of the allowed exposure do these measured levels and durations represent, and does the percentage cross a threshold? The page recommends using calibrated, task-representative level and duration measurements, splitting materially different levels into separate entries, confirming the applicable workplace criterion first, and keeping the standard, levels, durations, and percentage in the same record.
Use the decibel calculator when the question is logarithmic arithmetic: what ratio does a dB change represent, what dB value does a ratio correspond to, or how do two independent sound levels combine? The page notes that decibels appear in acoustics, electronics, radio links, audio engineering, and vibration, and that the combine result depends on the levels being compatible measurements with the same weighting and reference.
Limits and disclaimer
Neither calculator replaces a formal noise assessment. The noise exposure page states that variable, impulsive, and non-occupational noise can require methods not represented, that a few entered periods may not represent a full shift, and that it does not select hearing protection or apply a noise-reduction-rating method; escalate hearing-conservation and protective-equipment decisions to a qualified safety professional. The decibel page states it performs generic logarithmic arithmetic without A-weighting, C-weighting, time averaging, microphone calibration, or occupational exposure rules, and that phase cancellation, coherent sources, and room acoustics are not modeled. In safety contexts, use measured exposure data and standards-based guidance.