In addition to subtracting dB, by what percentage does OSHA require derating to estimate actual attenuation?

To understand the required derating percentage in addition to subtracting decibels (dB) for estimating actual attenuation, it’s important to consider OSHA's standards for hearing conservation. The Occupational Safety and Health Administration (OSHA) recommends that when measuring the effectiveness of hearing protection devices, a derating percentage is applied to ensure a more accurate representation of real-world attenuation.

OSHA specifically requires a derating of 50% from the manufacturer's stated attenuation levels. This is done because the laboratory conditions under which noise reduction ratings (NRRs) are derived may differ significantly from actual working environments where various factors such as fit, comfort, and user behavior can affect performance. Derating by this percentage helps to provide a more conservative and realistic estimate of how much sound the hearing protection device will block in practical use.

This requirement aims to enhance the safety and health of workers by ensuring that the levels of noise exposure are managed effectively, helping to prevent noise-induced hearing loss.