Exam Question Checklist

Exam 1998 Question 7

" How is the perceived loudness of pure tones related to their intensity and frequency? How does the perceived loudness of pure tones differ for listeners with a cochlear hearing loss?"

20 things you should mention:

• Loudness
  • threshold of audibility for pure tones
    • sets quietest threshold
  • threshold of pain (uncomfortable loudness level)
    • set loudest sound
  • also limited by frequency to between 20Hz
    • and 20,000Hz
  • diagram of dBSPL vs frequency, showing audibility
    • axes correct
  • 20µPa to 200Pa range (140dB)
  • equal steps of loudness on logarithmic scale, i.e. roughly equal on dB scale
  • equal loudness contours -> pure tones of different frequency
    • that have same subjective loudness
  • loudness measured in phons / less sensitive at very low and very high frequency / contours not equally spaced
• Impaired
  • cochlear loss = problem in detection of BM vibration
  • shifts threshold of audibility
  • but not threshold of pain
  • so very quiet tones -> inaudible
  • mid-loudness tones -> just audible
  • loud tones -> still painful
  • recruitment -> unnatural growth in perceived loudness with increasing intensity