At what decibel level must hearing protection be worn to prevent hearing threshold shift?

To prevent hearing threshold shift, hearing protection must be worn at a decibel level of 84 decibels. This threshold is established based on research indicating that sound levels exceeding 84 dB can begin to cause potential harm to hearing over prolonged exposure. Consistent exposure to noise above this level without adequate hearing protection can lead to permanent changes in hearing sensitivity or noise-induced hearing loss.

It's essential to recognize that while other levels, such as 80 dB or higher decibels like 90 dB and 95 dB, may also warrant caution and the use of hearing protection, 84 dB specifically marks the critical value at which protective measures are advised to minimize risk.