Transcript Mechanisms of sound change: a study on perceptual

A STUDY ON PERCEPTUAL
COMPENSATION FOR
/ /-FRONTING
IN AMERICAN ENGLISH
Reiko Kataoka
February 14, 2009
BLS 35
PERCEPTUAL COMPENSATION FOR COARTICULATION

Perceptual compensation for coarticulation: an effect of contextmoderated 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
 F1
PERCEPTUAL COMPENSATION
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 for
coarticulatory frongting in
alveolar context.
2) Listeners did so both in
Acoustic and Noise
contexts
Vdə
Vbə
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
250
F4 3500
200
F3 2319
150
F2 1200
100
F1
375
50
STIMULI
10 equal-step /i/ - /u/ continuum (Praat) cont.

Variable F2 and F3
F3
F2



2969 Hz ----------- 2319 Hz (0.18 Bark)
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 vowel
Alveolar:
[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
w/
precursor
Context
Conditions
Alveolar
Bilabial
‘deet’ /‘doot’ ‘beep’ /‘boop’
Acoustic (100)
[dVt]
[bVp]
Noise (100)
[NVN]
[NVN]
Fast (800-80)
[dVt]
[bVp]
Med. (1000-100)
[dVt]
[bVp]
Slow (1200-120)
[dVt]
[bVp]
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. (n=32: 18F, 14M; 19-49 yrs old)

H2
H3
Q2: RT
Q1
THIS IS HOW THE EXPERIMENT GOES (1)
Acoustic
Noise
Press [1]
Press [5]
for
‘deet’
for
‘doot’
THIS IS HOW THE EXPERIMENT GOES (2)
Acoustic
Noise
Press [1]
Press [5]
for
‘beep’
for
‘boop’
THIS IS HOW THE EXPERIMENT GOES (3)
Fast
Medium
Slow
Press [1]
Press [5]
for
‘deet’
for
‘doot’
RESULTS: NOISE VS. ACOUSTIC * CONTEXT
Percentage of /u/-Response by Context and Condition
Noise
Noise
Acustic
Real
/u/-Response
/u/-Response (%)(%)
10 0
Context
Alveolar
Bilabial
75
Dot/Lines show Means
50
25
0
1
2
3
4
5
6
7
8
9
StimulusStep
Step Number
Stimulus
Number
10
1
2
3
4
5
6
7
8
9
Stimulus
StepNumber
Number
Stimulus
Step
10
RESULTS: NOISE VS. ACOUSTIC * CONTEXT (RT)
Reaction Time for /u/-response
750

Context
Mean Reaction Time (msc)

684


710
694
643
500
Alv eolar
Bilabial
Error Bars s how Mean +/ - 1.0 SE
Bars s how Means
Effect of Contexts (Paired T-Test)
N: [t=-0.69 (31), p=0.499]
R: [t=-1.60 (31), p=0.123]
250
0
N ois e
R eal
Condition
RESULTS: PRECURSOR * CONTEXT
Percentage of /u/-Response by Condition and Context
Without Precursor
With Precursor
esponse (%)(%)
/u/-R
/u/-Response
10 0
Con
75
Dot/L
50
25
t=2.68 (31), p=0.012 *
t=0.91 (31), p=0.371
0
1
2
3
4
5
6
7
8
Stimulus Step N umber
9
10
1
2
3
4
5
6
7
8
Stimulus Step N umber
9
10
RESULTS: PRECURSOR * CONTEXT (RT)
Reaction Time for /u/-response

Mean Reaction Time (msc)
750.00


694
695

643
755
Context
Alv eolar
Bilabial
Error Bars s how 95. 0% C l of Mean
Bars s how Means
500.00
Effect of Contexts (Paired T-Test)
Without: [t=-1.6 (31), p=0.120]
With:
[t=-2.26 (31), p=0.031] *
250.00
0.00
W ithout Prec ursor
W ith Prec urs or
Condition
RESULTS: SPEECH RATE * CONTEXT
Percentage of /u/-Response by Context and Condition
Fast
Fast
Medium
Medium
/u/-Response
/u/-Response (%) (%)
100
Context
Alv eolar
Bilabial
75
D ot /Lines s how Means
50
25
0
Slow
Slow
/u/-Response
/u/-Response (%) (%)
100
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] *
75
50
25
0
1
2
3
4
5
6
7
8
Stimulus Step Number
Stimulus
Number
9
10
RESULTS: SPEECH RATE * CONTEXT (RT)
Reaction Time for /u/-response
Context

750
Rea ction Time (msc )



634
755
695
611

661

667
500
Alv eolar
Bilabial
Error Bars s how 95.0% Cl of Mean
Bars show Means
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
250
0
Fast
Medium
Speech Rate
Slow
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:



Reaction Time for /u/-response

1)
2)
3)

Greater shift with precursor sentences than without it.
Progressively greater boundary shift as speech rate increases
Significant context effect (A <B) 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?
Thank you!!