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Exam 1998 Question 2

" Frequency response graphs are useful for the description of systems. Explain how they may be used to: (i) assess the quality of audio equipment; (ii) explain the acoustics of speech production."

20 things you should mention:

  • Frequency Response
    • Frequency response graphs describe how a system:
      • changes the amplitude (output cf input)
      • of pure tones
      • at a range of frequencies
      • response is ratio O/I
      • and commonly expressed in decibels
  • Assess audio
    • generate a FR for audio equipment by measuring response to pure tones at a arange of frequencies
    • and plotting a graph (gfrequency characteristic)
    • ideally audio equipment makes no change
    • has a response that is flat
    • real systems are also band-limited for practical reasons
    • measure bandwidth at 3dB points
    • response of chain of systems = product of responses
  • Source Filter
    • source-filter model
    • independence of source and filter
    • filter corresponds to frequency response of vocal tract
    • shapes the excitation generated by larynx
    • filter response a function of articulatory configuration
      • and hence responsible for encoding much phonetic information
    • diagram

© 2000 Mark Huckvale University College London