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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
- threshold of pain (uncomfortable loudness level)
- also limited by frequency to between 20Hz
- diagram of dBSPL vs frequency, showing audibility
- 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
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