Quiz 10

• Pure Tone Audiometry


  Key hearing test to identify hearing threshold levels of an individual
• Pure Tone Audiometry


  • Tells us the degree, type, and configuration of hearing loss
  • Subjective behavioral measurement because it relies on patients' responses to stimuli
  • Helps aid in hearing aid selection, identifying functional hearing loss, and determining site of lesions
• Pure Tone Audiometry


  1. Start at 1000 Hz at 40 dB HL, and tell patient to respond when they hear something

  2. Every time the patient can hear the sound, decrease by 10 dB

  3. Every time they cannot hear the sound, increase by 5 dB

  4. The minimum dB level at which the patient responds 50% of the time is their threshold at that frequency

  5. Repeat steps for 2000, 4000, 8000, 250, & 500 Hz tones
• Pure Tone Audiometry (cont.)

  1. Compute pure tone average (PTA) by averaging threshold of 500, 1000, and 2000 Hz tones

  2. Repeat steps 1-4 using bone conduction

  3. Do BC and AC masking if required

  4. Make diagnosis including presence/absence of HL, ear(s), severity, pattern, type, etc.
• Masking


  • When a "better ear" might inadvertently assist the "more affected ear," your results might not be as accurate
  • Solution: providing masking noise in better ear
  • Typically used with over-ear headphones when 40 dB difference between ears exists (or with insert headphones when 55 dB difference exists)
• Testing at Mid Frequencies


  If two of the patient's back-to-back testing frequencies have a difference of 25 dB or more, mid frequencies should be tested, too
• Amounts of Hearing Loss

  • Normal hearing: -10 to +15 dB HL
  • Minimal hearing loss: 16– 25 dB HL
  • Mild hearing loss: 26 – 40 dB HL
  • Moderate hearing loss: 41 – 55 dB HL
  • Moderate-severe hearing loss: 56 – 70 dB HL
  • Severe hearing loss: 71 – 90 dB HL
  • Profound hearing loss: > 90 dB HL
• Interpreting Audiograms


  • No gap between air and bone conduction, Thresholds of 30 dB HL or higher
  • Gap between air and bone conduction, Air conduction impaired
  • No gap between air and bone conduction, One ear typical, other higher than 50 dB HL
  • Gap between air and bone conduction, Both impaired, though to varied degrees
• Speech Banana


  Diagram demonstrating the dB HL at various frequencies required to hear speech sounds
• Strengths of Pure Tone Audiometry

  • Establish hearing status
  • ID type, pattern, & severity of loss
  • Gain frequency-specific information
  • Extremely useful for differential diagnosis
• Limitations of Pure Tone Audiometry

  • Less sensitive in early stages of hearing loss
  • Cannot diagnose retrocochlear pathologies or auditory path issues
• Screenings


  • Often less thorough than true pure tone tests
  • 500 Hz (25 dB threshold)
  • 1000 Hz (20 dB threshold)
  • 2000 Hz (20 dB threshold)
  • 4000 Hz (20 dB threshold)