pure tone audiometry (PTA)

Last reviewed 03/2023

• pure-tone threshold audiometry is the measurement of an individual's hearing sensitivity for calibrated pure tones (1)
• assesses hearing loss by air and bone conduction.
• pure tone signals between 125Hz and 12kHz and at variable intensities are fed to the patient either via a vibrator applied to the mastoid process - for bone conduction - or via earphones - for air conduction. The intensity at which 50% of tones for a particular frequency are reported is charted as the threshold for that frequency on an audiogram.
• the symbols used on most audiograms are:
  • x - left, air conduction
  • o - right, air conduction
  • ] - left, bone conduction
  • [ - right, bone conduction
• its results have significant influence on the medical, legal, educational, occupational, social, and psychological outcomes (1)

Notes:

• degrees of Hearing Loss (2):

  Normal Hearing	-10-26 dB
  Mild Hearing Impairment	27-40 dB
  Moderate Hearing Impairment	41-55 dB
  Moderately Severe Impairment	56-70 dB
  Severe Hearing Impairment	71-90 dB
  Profound Hearing Impairment	>= 91 dB

Reference:

• (1) The American Speech-Hearing-Language Association (ASHA).Guidelines for Manual Pure-Tone Threshold Audiometry. 2005
• (2) Katz, J. Handbook of Clinical Audiology, Williams and Wilkins, 1985.