What is the criterion for average hearing loss?

The criterion for average hearing loss in the context of medical examinations, particularly in determining whether a commercial driver's license can be issued, is defined as less than 40 dB. This threshold indicates that an individual has a normative level of hearing capability, allowing them to function adequately in various auditory environments, which is crucial for safety during driving and other related activities.

A hearing loss average greater than this threshold would suggest potential impairment that could interfere with the driver’s ability to hear important sounds, such as sirens or horns, and could pose a risk to themselves and others on the road. Therefore, a standard of less than 40 dB represents the minimum requirement for hearing capability, thus making it the correct answer in assessing hearing loss criteria.