Frequency Range
In audiology, frequency refers to the number of sound wave cycles per second, measured in Hertz (Hz). Humans with normal hearing can detect sounds roughly between 20 Hz and 20,000 Hz, though the most important range for understanding speech is approximately 500 Hz to 4,000 Hz.
Audiological assessments typically test hearing thresholds at frequencies from 250 Hz to 8,000 Hz. Low-frequency sounds include vowels and environmental sounds such as traffic rumble. High-frequency sounds include consonants like "s," "sh," "f," and "th," which carry much of the clarity in speech. Hearing loss often affects specific frequency ranges rather than all frequencies equally. High-frequency hearing loss, for example, makes it harder to hear consonants, leading to speech that sounds muffled even when the volume seems adequate.
A person's frequency-specific hearing thresholds are plotted on an audiogram, giving the audiologist a complete profile of where hearing is strongest and where it is reduced. This profile directly guides hearing aid programming.
