Noise Exposure & Hearing Protection Calculator

Under OSHA 29 CFR 1910.95, the Permissible Exposure Limit (PEL) for noise is 90 dBA as an 8-hour Time-Weighted Average (TWA).

The OSHA Action Level is an 8-hour TWA of 85 dBA (or a 50% noise dose), which triggers mandatory Hearing Conservation Program enrollment, annual audiometric testing, and free hearing protection.

OSHA uses a 5 dBA exchange rate (doubling rate): for every 5 dBA increase in noise level, permissible exposure time is cut in half (e.g. 90 dBA = 8 hrs, 95 dBA = 4 hrs, 100 dBA = 2 hrs).

Dose % = 100 × Σ(C_i / T_i), where C_i is actual exposure time at sound level L_i and T_i is permissible time T = 8 / 2^{(L_i - 90)/5}.

TWA = 90 + 16.61 × log10(Dose / 100). A Dose of 100% equals a TWA of 90.0 dBA.

NRR measures hearing protector attenuation. OSHA recommends derating manufacturer NRR by 50% for field use: Effective dBA = C-weighted Noise - NRR or A-weighted Noise - (NRR - 7)/2.

OSHA 29 CFR 1926.52 governs occupational noise exposure in construction, incorporating identical dBA exposure limits.

Hearing protection is mandatory for employees exposed to an 8-hour TWA of 90 dBA or higher, or 85 dBA for employees who have experienced a Standard Threshold Shift (STS).

OSHA Standard 1910.95 sets the 8-hour time-weighted average (TWA) PEL at 90 dBA using a 5 dB exchange rate.

OSHA mandates implementing a Hearing Conservation Program when 8-hour noise exposure reaches or exceeds 85 dBA (50% dose).

Under OSHA's 5 dB rule, allowable exposure time is cut in half for every 5 dBA increase in noise level (e.g., 90 dBA = 8 hrs, 95 dBA = 4 hrs, 100 dBA = 2 hrs).

Dose D (%) = 100 × Σ (C_i / T_i), where C_i is actual exposure duration at a noise level and T_i is maximum allowed duration at that level.

NIOSH recommends a stricter 8-hour REL of 85 dBA with a 3 dB exchange rate (allowable time halves for every 3 dBA increase).

NRR measures laboratory sound attenuation. OSHA calculates real-world protection using: Effective dBA = Noise dBA - [(NRR - 7) / 2].

OSHA 1910.95(b)(2) prohibits worker exposure to unattenuated peak impulse or impact noise exceeding 140 dBC peak sound pressure level.

TWA = 16.61 × log10(D / 100) + 90 dBA. For example, a 100% dose yields TWA = 90 dBA, while a 50% dose yields TWA = 85 dBA.

An OSHA program requires annual audiometric testing, baseline audiograms, training, mandatory hearing protection, and environmental noise monitoring.

Decibels add logarithmically. Operating two identical 90 dBA machines produces a combined noise level of 93 dBA (L_total = 10 × log10(10^(9.0) + 10^(9.0))).