Exam Question Checklist

Exam 1999 Question 1

"Describe the acoustics of fricative production. Contrast the different characteristics of: a) the glottal fricative; and b) sibilant fricatives; and c) dental or labio-dental fricatives. "

20 things you should mention:

• Source Filter
  • source-filter model definition
  • source is turbulence
  • - generated in constriction
  • - and sometimes by jet hitting an obstacle
  • - typical spectrum
  • voiced fricatives also have larynx excitation
  • - airflow modulation affects turbulence = pulsing
  • filter in predominantly front cavity
  • - typical frequency response
• Contrast characteristics
  • glottal fricative, source at glottis
  • - vocal folds approximated but small gap causes turbulent flow
  • - filter is whole vocal tract
  • - vowel-like response/picture/coarticulation
  • sibilant fricatives: /s/ and /S/
  • - source if turbulence and jet hitting an obstacle
  • - upper teeth for /s/, lower teeth for /S/
  • - filter is small, resonant front cavity/typical freq response
  • dental/labio-dental fricatives: /f/ & /T/
  • - source is wide slit/weak
  • - filter is practically non-existent/broad shape/high frequency