Final answer:
Air conduction threshold testing commonly ranges from 250 Hz to 8000 Hz. A frequently used starting frequency is 1000 Hz as it falls within the critical range of conversational speech. Audiograms illustrate individual hearing thresholds and can indicate various types of hearing loss, such as the common age-related presbycusis.
Step-by-step explanation:
During air conduction threshold testing, part of audiometric evaluations, the frequencies tested typically range from 250 Hz to 8000 Hz. The threshold of hearing is the quietest sound that can be heard about 50% of the time by a person with normal hearing, and audiograms plot this threshold across various frequencies. The testing begins with lower frequencies and progresses to higher ones. While there is not one standardized starting frequency for all tests, a common reference frequency to begin with is 1000 Hz because it is well within the range of conversational speech and has clinical significance.
As shown in the provided references, the audiogram graphs represent differing levels of hearing loss amongst individuals and plots their thresholds relative to the normal threshold. For instance, noise-induced hearing loss often displays a dip in hearing sensitivity around the 4000 Hz frequency. Tests like air and bone conduction assessments can help differentiate between the types of hearing loss, whether due to middle ear or nerve damage. A condition called presbycusis, characterized by age-related hearing decline, typically shows more severe hearing loss at higher frequencies.