Griffioen 9 November 1994

Quiz 4

  • State Fourier's theorem for periodic waveforms.
  • A complex waveform has a pattern that repeats every millisecond. What frequencies could be present in the Fourier spectrum of this wave?
  • Why is the just noticeable difference in pitch so much less than the critical band?
  • Explain the features of the Fletcher-Munson diagram (see back). Why do the curves go up at low and high frequencies? Why are there dips at 4000 and 12,000 Hz?
  • What sound intensity level is required for you to hear a 20 Hz sine wave at the same loudness as a 20 dB sound at 1000 Hz? Extra Credit: What is noise? Argue from Fourier's theorem that the waveform for noise cannot be periodic.
    The Department of Physics
    matt@physics.wm.edu