Exam Question Checklist

Exam 1999 Question 7

"Describe what equipment and what method you would use to make the following measurements: a) the measurement of the intensity of a sound using the dBSPL scale; and b) the measurement of hearing impairment for pure tones using the dBHL scale: and c) the measurement of the perceived loudness of a pure tone using the phon scale."

20 things you should mention:

• Intensity
  • microphone
  • voltmeter
  • calibrated sounds
  • make voltage ratio to calibrated sounds
  • express in dB re calibrated sound -> dBSPL
  • dBSPL formula, re: 20microPa
• dBHL
  • sinewave generator
  • attenuator
  • headphones
  • means of calibration to known dBSPL
  • pure tone audiometric procedure to find threshold
  • compare to thresholds of adult normals at that frequency
  • dBHL = individual threshold (dBSPL) - average threshold (dBSPL)
• Loudness
  • sinewave generators
  • attenuator
  • headphones
  • play two tones, one fixed at test frequency and level
  • one at 1kHz variable in amplitude
  • get subject to match for loudness
  • phon = dbSPL of 1kHz match tone - dBSPL of threshold at 1kHz