A STUDY ON PERCEPTUAL COMPENSATION FOR

/ /-FRONTING IN AMERICAN ENGLISH

Reiko KataokaFebruary 14, 2009

BLS 35

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

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

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

Stimuli: [i] – [u] continua (with following [də] or [bə])

Factors: Alveolar, Bilabial Acoustic or Noise

Findings:1) Listeners compensated forcoarticulatory frongting inalveolar context.2) Listeners did so both inAcoustic and Noisecontexts

VbəVdə

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?)

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 250F4 3500 200F3 2319 150F2 1200 100F1 375 50

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)

STIMULUS CVC

Add onset and coda to the vowelAlveolar: [dit] – [dut] Alveolar in Noise: [NiN] – [NuN]Bilabial: [bip] – [bup] Bilabial in Noise: [NiN] – [NuN] (Vowel onset to C2 release = 170 msc)

EXPERIMENTAL DESIGN

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 – blockedListeners: Native speakers of Am-Engl. (n=32: 18F, 14M; 19-49 yrs

old)

ContextConditions Alveolar

‘deet’ /‘doot’

Bilabial ‘beep’ /‘bo

op’w/o

precursor

Acoustic (100) [dVt] [bVp] Noise (100) [NVN] [NVN]

w/ precurso

r

Fast (800-80) [dVt] [bVp] Med. (1000-

100)[dVt] [bVp]

Slow (1200-120)

[dVt] [bVp] H1

H3

H2Q1

Q2: RT

THIS IS HOW THE EXPERIMENT GOES (1)

Acoustic

Noise

Press [1] Press [5] for for ‘deet’ ‘doot’

THIS IS HOW THE EXPERIMENT GOES (2)

Acoustic

Noise

Press [1] Press [5] for for ‘beep’ ‘boop’

THIS IS HOW THE EXPERIMENT GOES (3)

FastMediumSlow

Press [1] Press [5] for for ‘deet’ ‘doot’

RESULTS: NOISE VS. ACOUSTIC * CONTEXT

Percentage of /u/-Response by Context and Condition

Noise Real

AlveolarBilabial

Context

Dot/Lines show Means

1 2 3 4 5 6 7 8 9 10

Stimulus Step Number

0

25

50

75

100

/u/-

Res

po

ns

e (

%)

1 2 3 4 5 6 7 8 9 10

Stimulus Step Number

Noise Acustic

/u/-

Resp

onse

(%

)

Stimulus Step Number Stimulus Step Number

RESULTS: NOISE VS. ACOUSTIC * CONTEXT (RT)

Reaction Time for /u/-response

Alveolar

Bilabial

Context

Error Bars show Mean +/- 1.0 SE

Bars show Means

Noise Real

Condition

0

250

500

750

Mea

n R

eact

ion

Tim

e (m

sc)

Effect of Contexts (Paired T-Test)N: [t=-0.69 (31), p=0.499]R: [t=-1.60 (31), p=0.123]

684710

643 694

RESULTS: PRECURSOR * CONTEXT

Percentage of /u/-Response by Condition and Context

Without Precursor With Precursor

Alveolar

Bilabial

Context

Dot/Lines show Means

1 2 3 4 5 6 7 8 9 10

Stimulus Step Number

0

25

50

75

100

/u/-

Res

po

ns

e (

%)

1 2 3 4 5 6 7 8 9 10

Stimulus Step Number

t=0.91 (31), p=0.371

t=2.68 (31), p=0.012 *

/u/-

Resp

onse

(%

)

RESULTS: PRECURSOR * CONTEXT (RT)

Reaction Time for /u/-response

AlveolarBilabial

Context

Error Bars show 95.0% Cl of Mean

Bars show Means

Without Precursor With Precursor

Condition

0.00

250.00

500.00

750.00

Mea

n R

eact

ion

Tim

e (m

sc)

643694 695

755

Effect of Contexts (Paired T-Test)Without: [t=-1.6 (31), p=0.120]With: [t=-2.26 (31), p=0.031] *

RESULTS: SPEECH RATE * CONTEXTPercentage of /u/-Response by Context and Condition

Fast Medium

Slow

Alveolar

Bilabial

Context

Dot/Lines show Means

0

25

50

75

100

/u/-

Re

sp

on

se

(%

)

1 2 3 4 5 6 7 8 9 10

Stimulus Step Number

0

25

50

75

100

/u/-

Re

sp

on

se

(%

)

Effect of Contexts (Paired T-Test)Slow: [t=-0.078 (31), p=0.938]Medium: [t=2.684 (31), p=0.012] *Fast: [t=4.657 (31), p<0.001] *

/u/-

Resp

onse

(%

)

/

u/-

Resp

onse

(%

)

Fast

Slow

Medium

Stimulus Number

RESULTS: SPEECH RATE * CONTEXT (RT)

Reaction Time for /u/-response

AlveolarBilabial

Context

Error Bars show 95.0% Cl of Mean

Bars show Means

Fast Medium SlowSpeech Rate

0

250

500

750

Rea

ctio

n T

ime

(msc

)

634 667661

755

695

611

Effect of Contexts (Paired T-Test)Slow: [t=-0.157 (31), p=0.876]Medium: [t=-2.257 (31), p=0.031]*Fast: [t= 0.686 (31), p=0.498

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 <B) in majority of conditions

1) 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.

2) Compensation could be incomplete. 3) Perceptual Compensation may be related to contrast

enhancement.

On the linguistic theory of sound change: Assimilatory sound change by incomplete correction?

Thank you!!