Exam Question Checklist

Exam 1999 Question 5

"What is meant by locus frequency? How does locus frequency information aid the listener in identifying consonants? How can the sensitivity of listeners to locus frequency be established by an experiment?"

20 things you should mention:

• Locus Frequency
  • relates to formant patterning of VC and CV transitions
  • formant transitions arise as articulators move from vowe to consonant (and vice versa)
  • transition shape depnds on place and manner/tongue movement, etc
  • hence different vowels show different patterns for same consonant
  • but similar 'directions' (starting frequencies) for different vowels, same consonant
  • this direction known as locus frequency
• Perception
  • F1 locus frequency is 0Hz for all obstruents
  • therefore low F1 locus indicates manner
  • F2 & F3 locus frequencies differ for different places
  • - therefore place cue
  • locus frequencies common even if different vowels
  • therefore invariant cues.
• Measurement
  • need stimuli that only differ in locus frequency
  • see if they give rise to different perceptions
  • use synthetic speech to control/neutralise other factors
  • create continuum between two locus frequency positions
  • - for example date/gate
  • give random, multiple presentations to group
  • show change in perception on fixed choice task
  • repeat experiment for different vowels.