What is the maximum permissible hearing loss for a commercial driver under DOT regulations?

The maximum permissible hearing loss for a commercial driver under DOT regulations is specifically defined as no greater than 40 dB in the better ear at the frequencies of 500, 1000, and 2000 Hz. This standard is established to ensure that commercial drivers possess adequate hearing ability to be aware of their surroundings, including auditory signals from other vehicles, warnings, and communication with passengers or other road users.

It is important that drivers can hear sounds that are critical for safe driving, and this regulation reflects the necessity for a balance between safety and the ability to operate a commercial vehicle effectively. The focus on the better ear also acknowledges that individuals may have varying levels of hearing loss in each ear but can still meet safety standards if the better ear is within the permissible limits.

The other options suggest different thresholds, which do not align with the established DOT regulation. For instance, a threshold of 30 dB or 20 dB would be stricter than what is required, while a limit of 50 dB in the worse ear does not meet the criteria that prioritize hearing capacity in the better ear. Therefore, the correct answer highlights the specific requirement crucial for ensuring the safety of both the driver and the public while operating a commercial vehicle.