What is Temporary Threshold Shift?

Temporary threshold shift is a fancy way of saying that someone experienced short-term hearing loss from exposure to loud noise. The noise source can be instantaneous or prolonged.

Here are five findings from original research by Hallowell Davis on temporary threshold shift:

  1. Higher frequencies (ex 2-4 kHz) cause a more significant threshold shift than low frequencies (ex 500 Hz).
  1. Half-octave rule: Audiometric frequency region that demonstrated hearing loss occured between half to one octave higher than the stimulus frequency.
  1. Significant intra- and inter-subject variability.  Sheds some light about how we do not fully understand the functions of the sensorineural mechanism of tinnitus.
  1. Majority of noise notch hearing loss occurred in the 3-6 kHz region.  This corroborates with humans who obtain noise notches in this region with exposure to BBN.
  2. The most fascinating section of this study for me was correlating the ear canal length (and associated resonance) with a noise notch center frequency.  I always think of this in terms of music.  Instruments with longer tubes have lower frequency resonance.  Therefore, someone with a short ear canal length may have a noise notch and associated tinnitus in a relatively higher-pitch region.

DAVIS H, MORGAN CT. Temporary deafness following exposure to loud tones and noise. Laryngoscope. 1946;56:19-21.

Here is a link to updated research on temporary threshold shift: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4988324/

Dr. Ben Thompson, Au.D.

Dr. Ben Thompson, Au.D.

Dr. Ben Thompson is an audiologist in California and founder of Pure Tinnitus. Dr. Thompson has a comprehensive knowledge of tinnitus management. He completed his residency at University of California at San Francisco (UCSF) and is a past board member of the California Academy of Audiology. Via telehealth, Dr. Thompson provides services to patients with hearing loss and tinnitus.

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