Extended High Frequency Audiometry
Extended high frequency (EHF) audiometry tests hearing at frequencies above the standard audiometric range. Conventional audiometry covers 250 Hz to 8,000 Hz. Extended high frequency audiometry extends this to include 9,000 Hz, 10,000 Hz, 12,500 Hz, 14,000 Hz, and in some protocols up to 16,000 or 20,000 Hz.
Cochlear hair cell damage from noise, aging, or ototoxic medications (drugs that can damage the inner ear, such as certain chemotherapy agents and aminoglycoside antibiotics) often begins in the high-frequency basal region of the cochlea, which processes frequencies above 8,000 Hz, before measurable loss appears in the conventional audiometric range. EHF audiometry can detect this early damage, allowing clinicians to monitor patients receiving potentially ototoxic treatments, identify early noise-induced changes in occupational hearing conservation programs, and track the progression of hearing loss in populations at risk.
EHF testing requires calibrated high-frequency audiometers and insert earphones designed for the extended range. Standard audiometers and headphones do not deliver reliable output at these frequencies. In Canada, extended high frequency audiometry is available in some specialty audiology clinics and hospital programs, particularly those managing oncology patients receiving ototoxic chemotherapy.
