threshold shift
Change in hearing sensitivity from baseline measurements, indicating hearing loss progression or recovery.
Full Definition
Threshold shift represents a measurable change in hearing thresholds compared to baseline audiometric measurements, typically expressed in decibels at specific frequencies. Temporary threshold shifts (TTS) occur after noise exposure but recover within hours to days, while permanent threshold shifts (PTS) indicate irreversible hearing loss. Significant threshold shifts, defined as changes of 10 dB or more at any frequency or 5 dB at two consecutive frequencies, trigger medical evaluation and intervention protocols. Standard threshold shifts of 10 dB average at 2000, 3000, and 4000 Hz are used in occupational hearing conservation programs to identify noise-induced hearing loss requiring immediate attention.
Usage
Usage note: Always specify whether temporary (TTS) or permanent (PTS); express magnitude and affected frequencies clearly.
In Context
- "The employee's annual audiogram revealed a 15 dB threshold shift at 4000 Hz, requiring noise exposure investigation." — Occupational health screening report
- "Significant threshold shifts must be verified through repeat testing within 30 days of identification." — Hearing conservation program protocol