Final answer:
The minimum standard for hearing evaluation via audiometry involves testing frequencies from 250 to 8000 Hz, capturing hearing thresholds on an audiogram. A normal threshold is 0 dB.
Step-by-step explanation:
The minimum standard for hearing evaluation via audiometry typically involves testing a range of frequencies, usually from 250 to 8000 Hz. These tests are designed to determine the hearing threshold, which is the softest sound that can be heard by an individual. Audiometric evaluations are depicted graphically in an audiogram, where normal hearing is represented by a threshold of 0 dB across all frequencies. When hearing loss is present, such as from noise exposure, an audiogram may show specific dips in particular frequencies, for example, a common dip at 4000 Hz. Noise-induced hearing loss often affects both ears and can alter the intensity levels required for sounds to be just barely audible.
Regarding occupational standards, several government agencies and health-related professional associations recommend that 85 dB should not be exceeded for 8-hour workdays unless hearing protection is utilized. This limit is set to prevent noise-induced hearing loss in the workplace. For personal hearing evaluations, audiometry is used to diagnose various forms of hearing loss, including age-related loss, known as presbycusis, which progressively diminishes the ability to hear higher frequencies.