a study on perceptual compensation for fronting in American English

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a study on perceptual compensation for /
/-fronting in American English

• Reiko Kataoka
• February 14, 2009
• BLS 35

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PERCEPTUAL COMPENSATION FOR COARTICULATION

• Perceptual compensation for coarticulation an
  effect of context-moderated perception that
  compensate for coarticulatory influence of the
  speech sounds.
• Perceptual correction (Ohala 1981 182)
• Failure to compensate , erroneous compensation ?
  misperception
• Why care perceptual compensation?
• To understand how humans achieve faithful sound
  transmission
• To understand how misperception could occur ?
  sound change

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EXAMPLES OF PERCEPTUAL COMPENSATION

• F1 of precursor influences i/e decision
  (Ladefoged Broadbent, 1957)
• Speech rate influences i/u decision in w_w
  context (Lindblom Studdert-Kennedy, 1967)
• Influence by
• adjacent segment Mann Repp, 1980 Lotto
  Kluender, 1998 Beddor Krakow,1999 Harrington
  et al., 2008
• Lexical status Ganong, 1980 Elman McClelland,
  1988
• Precursor sentence Ohala Shriberg, 1990

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PREVIOUS STUDY ON ALVEOLAR /
/-FRONTING (OHALA FEDER, 1994)

• Stimuli i u continua (with following d?
  or b?)
• Factors
• Alveolar, Bilabial
• Acoustic or Noise
• Findings
• 1) Listeners compensated for
• coarticulatory frongting in
• alveolar context.
• 2) Listeners did so both in
• Acoustic and Noise
• contexts

Vd?
Vb?
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HYPOTHESIS

• H1 The /i-u/ boundary would be more leftward for
  alveolar context than for bilabial context.
• H2 The similar boundary shift would occur both
  in Acoustic and Noise conditions.
• H3 The boundary discrepancy would become
  progressively greater as speech rate increase
  from slow to medium to fast.
• Exploration
• H4 Whether vowel perception is influenced by
  presence or absence of precursor sentence.
  (acoustic mode vs. speech mode?)
• H5 Whether Reaction Time (RT) for /u/-response
  is influenced by context or not. (perceptual
  contrast?)

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STIMULI

• 10 equal-step /i/ - /u/ continuum (Praat)
• Separate a source from natural utterance.
• Apply a filter (5 peak fequencies and bandwiths)
• Duration 100 msc

Formant (Hz) bandwidth (Hz) F5 4500
250 F4 3500 200 F3 2319
150 F2 1200 100 F1 375 50
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STIMULI

• 10 equal-step /i/ - /u/ continuum (Praat) cont.
• Variable F2 and F3
• F3 2969 Hz ----------- 2319 Hz (0.18
  Bark)
• F2 2372 Hz ----------- 1200 Hz (0.5
  Bark)
• Vowel duration 100 msc (also 80 msc and 120
  msc)
• Amplitude contour first and last 15 ms
• F0 contour 130? 90 Hz
• 
  
  
• F3 2969 2888 2808 2732
  2658 2586 2516 2448 2382
  2319 (Hz)
• F2 2372 2201 2042 1895
  1759 1632 1513 1402 1298
  1200 (Hz)

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STIMULUS CVC
Add onset and coda to the vowel Alveolar dit
dut Alveolar in Noise NiN
NuN Bilabial bip bup Bilabial in
Noise NiN NuN (Vowel onset to C2 release
170 msc)
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EXPERIMENTAL DESIGN
H2
Q1
H3
Q2 RT
H1

• w/o Precursor Stimulus presented in isolation
• Task two-alternative forced-choice between /i/
  and /u/
• w/Precursor Stimulus presented after I guess
  the word is _____
• Trials 10 tokens x 4 repetition 40 trials per
  cell
• Block Context blocked Acoustic vs. Noise
  mixed
• Fast, Medium, Slow blocked
• Listeners Native speakers of Am-Engl. (n32
  18F, 14M 19-49 yrs old)

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THIS IS HOW THE EXPERIMENT GOES (1)

• Acoustic
• Noise
• Press 1 Press 5
• for for
• deet doot

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THIS IS HOW THE EXPERIMENT GOES (2)

• Acoustic
• Noise
• Press 1 Press 5
• for for
• beep boop

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THIS IS HOW THE EXPERIMENT GOES (3)

• Fast
• Medium
• Slow
• Press 1 Press 5
• for for
• deet doot

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RESULTS NOISE VS. ACOUSTIC CONTEXT

• Percentage of /u/-Response by Context and
  Condition

Noise
Acustic
/u/-Response ()
Stimulus Step Number Stimulus Step
Number
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RESULTS NOISE VS. ACOUSTIC CONTEXT (RT)

• Reaction Time for /u/-response

710
684
694
643
Effect of Contexts (Paired T-Test) N t-0.69
(31), p0.499 R t-1.60 (31), p0.123
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RESULTS PRECURSOR CONTEXT

• Percentage of /u/-Response by Condition and
  Context

/u/-Response ()
t2.68 (31), p0.012
t0.91 (31), p0.371
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RESULTS PRECURSOR CONTEXT (RT)

• Reaction Time for /u/-response

755
694
695
643
Effect of Contexts (Paired T-Test) Without
t-1.6 (31), p0.120 With t-2.26 (31),
p0.031
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RESULTS SPEECH RATE CONTEXT

• Percentage of /u/-Response by Context and
  Condition

Fast
Medium
/u/-Response () /u/-Response ()
Slow
Effect of Contexts (Paired T-Test) Slow
t-0.078 (31), p0.938 Medium t2.684 (31),
p0.012 Fast t4.657 (31), plt0.001
Stimulus Number
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RESULTS SPEECH RATE CONTEXT (RT)

• Reaction Time for /u/-response

755
695
634
667
661
611
Effect of Contexts (Paired T-Test) Slow
t-0.157 (31), p0.876 Medium t-2.257 (31),
p0.031 Fast t 0.686 (31),
p0.498
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SUMMARY AND DISCUSSIONS

• No compensation when consonantal contexts were
  replaced by white noise and assumed contexts
  were given visually.
• Degree of boundary shift varies across stimuli
  and experimental condition
• Greater shift with precursor sentences than
  without it.
• Progressively greater boundary shift as speech
  rate increases
• Reaction Time for /u/-response
• Significant context effect (A ltB) in majority of
  conditions
• Degree of Compensation for coarticulation may be
  influenced by speechlike-ness of the stimuli.
  Compensation is triggered when linguistic
  expectation plays a role in perception.
• Compensation could be incomplete.
• Perceptual Compensation may be related to
  contrast enhancement.
• On the linguistic theory of sound change
  Assimilatory sound change by incomplete
  correction?

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• Thank you!!