What Actually Protects Ears: Real-World Attenuation of Foam Plugs, Cotton Wool, and Cloth Against a Workshop Noise Spectrum

Workers in small workshops often rely on whatever is at hand to protect their hearing. This study computes protected exposure for four options against a stated workshop octave-band spectrum that sums to 103.29 dBA: foam earplugs fitted well, the same foam plugs fitted poorly, cotton wool, and a cloth wrap. Real-world, derated attenuation by octave band is stated for each option in the accompanying script, and protected levels are obtained by subtracting that attenuation band by band and re-summing with A-weighting. Well-fitted foam plugs give an effective A-weighted attenuation of 30.55 dB and a protected level of 72.74 dBA, an 8-hour dose of 5.9 percent of the stated 85 dBA criterion. Poorly fitted foam plugs give only 8.96 dB of effective attenuation and a protected level of 94.33 dBA, a dose of 863.3 percent. Cotton wool gives 3.47 dB and 99.82 dBA, a dose of 3071.5 percent. A cloth wrap gives 3.18 dB and 100.11 dBA, a dose of 3283.6 percent. Cotton wool and cloth wraps therefore do not work as hearing protection against this spectrum; the numbers are a plain disproof of their use for that purpose. The minimum effective attenuation this workplace requires is 18.29 dB, or 21.29 dB with a 3 dB margin for variation in fit. SIMULATED, NOT MEASURED.