Transcript An Investigation of the Effects of Multiple Productions on

An Investigation of the Effect of Multiple Productions
on the Single Word Production of People with
Acquired Speech Sound Production Difficulties:
An Analysis of 2 Cases
Lynn Li Lim1,2, Karen Croot1,2,3, Sallyanne Palethorpe1,2, Max Coltheart1,2
1. Macquarie Centre for Cognitive Science (MACCS), Macquarie University
2. Speech Hearing and Language Research Centre (SHLRC), Macquarie University
3. School of Psychology, The University of Sydney
Acoustic Analysis

Speech disorders may share similar
symptoms of impaired speech production
 To determine the speech disorder associated
with the symptom  examine speech
segment productions acoustically
 Gives more concrete information on speech
qualities attributed to phonological &
articulatory deficits
 More reliable than impressionistic phonetic
transcription (Haley et al, 2001)
Acoustic Speech Analysis

Most common acoustic investigations are on
contrastive features to determine if speech
segment errors are:

Phonemic – substitution of one phoneme for
another

Phonetic – impaired articulation of a speech
sound
(Baum et al, 1990; Tuller, 1984)
Variability in Speech Production

Unimpaired speech production can be
somewhat variable (Auzou et al, 2000)
 Acoustic studies usually rely on multiple
productions of speech tokens to overcome
this variability
 People with speech disorders are far more
variable in their productions than controls
(Ryalls, 1986)

But disordered speech analyses have not
addressed the issue of possible effects of
multiple productions
 And their results have been inconsistent
Multiple Production

Not known if eliciting multiple word
productions from these people affects their
speech sound production difficulties
H1: Fatigue – deterioration of speech
production
 H2: Practice – improvement in speech
production
 H0: No effect on speech production

Previous Studies

Some examples for Vowel Duration
Study:
Ryalls (1986)
Tuller (1984)
Williams & Seaver
(1986)
Speakers
5 N/FL
7 FL
5 N/FL
5 FL
7 N/FL
14 FL
Repetitions 5
per word
16
1
Mean
Durations
N/FL & FL > CTRL
N/FL & FL > CTRL
2 N/FL > Others
Variability
N/FL > FL & CTRL
N/FL & FL > CTRL
N/FL & FL < CTRL
(Only some)
Multiple Production
Implication:
 If there are effects, then method of eliciting
speech tokens may confound the
investigation of the nature of the disorder
Other Features of Speech
Production

Previous acoustic studies address question
of whether speakers produce phonemic or
phonetic errors
 Other information about speech production
difficulties that are non-contrastive in nature
 These are not usually reported in most
acoustic studies
Research Questions
Q1: Does multiple repetition of target words
affect phonetic parameters of the speech
of people with impaired speech sound
production?
Q2: Are there other phonetic parameters in the
speech of these individuals that might be
indicative of the nature of the disorder but
not usually reported?
Speakers





AR
63 y.o., male
progressive aphasia with other mild cognitive
deficits 2.5 years after presentation
impaired syntax & phoneme discrimination
semantic abilities just below control range
moderate hearing loss
(35-50 dB loss at 4kHz, 55-70 dB loss at 6 kHz)
Speakers






HO
62 y.o., male
left middle cerebral artery infarct early 1996
unimpaired visuo-perceptual processing of
pictures & words
semantic abilities just below control range
impaired receptive phonological processing
moderate hearing loss
(45-55 dB loss at & above 4 kHz)
Material
Experiment 1 Experiment 2
Words
15
12
Repetitions (per session)
6
15
Sessions
5
5
* Words were presented in pseudo-random order among fillers
Task
Reading
Reading
Words used in current
study
bed, big, dark,
duck,pen, pig,
pick, saw, sea
buck, bug
puck, pad, pat
Speaker(s)
AR, HO
HO
Acoustic Procedure

Recordings digitised at 20,000 Hz

Spectrograms hand-labelled & analysed
using the EMU speech database system &
the R statistical analysis software

Acoustic dimensions analysed:
 Burst Release Duration (BRDUR)
 Vowel Duration (VDUR)
 Fricative Spectral Moments (FSM)
First SM (SM1): average spectral frequency
Q1: Statistical Analysis

Repeated Measures ANOVA
 To investigate for any significant differences
in the variance between sessions

Sphericity: assumption that variance is equal
between pairs of scores
(Field, 2000, p.324)
Q1: Results - Error-bar Plots
Example: Burst Release Duration of /d/ (AR)
duck
150.00
150.00
100.00
100.00
brdur
brdur
dark
50.00

50.00






0.00
0.00
-50.00
-50.00
A
B
C
session
D



E
A
B
C
session
D
E
Q1: Results - Error-bar Plots
Example: Burst Release Duration of /p/ (HO)
pen
pi g
150.00
pi ck
150.00
150.00




100.00



100.00

50.00
0.00

brdur
brdur
brdur

50.00
0.00
-50.00
C
session
D
E
50.00
0.00
-50.00
B


100.00

A


-50.00
A
B
C
session
D
E
A
B
C
session
D
E
Q1: Results - Error-bar Plots
Example: 1st Spectral Moment of /s/ (HO)
saw
sea
7000.00
7000.00
6000.00
6000.00


sm1
sm1

5000.00





5000.00


4000.00
4000.00
A
B
C
session
D
E
A
B
C
session
D
E
Q1: Results - Error-bar Plots
Example: Vowel Duration of /I/ (AR)
bi g
pi g
250.00
200.00
pi ck
250.00
250.00
200.00
200.00

150.00



150.00

vdur
vdur

vdur



150.00






100.00
100.00
1
2
3
session
4
5
100.00
1
2
3
session
4
5
1
2
3
session
4
5
Q1: Results - ANOVA
Vowel duration /I/ in “Big” (Speaker AR)
Descriptive Statistics
Mean
Std. Deviation
N
SESSION1
177.2333
25.69425
6
SESSION2
187.5333
31.51582
6
SESSION3
135.0167
20.12912
6
SESSION4
133.6800
25.64429
6
SESSION5
161.9833
21.51803
6
Mauchly's Test of Sphericity
Within Subjects Effect
Mauchly's W
Speaker AR (Big - VDUR)
Approx. Chi-Square
.013
df
Sig.
9
.127
14.954
Tests of Within-Subjects Effects
Source
Sum of Squares
df
Mean Square
Speaker AR (Big – VDUR)
14230.612
4
3557.653
Error
10466.874
20
523.344
F
6.798
Sig.
.001
Q1: Results - ANOVA
Pairw ise Comparisons
Measure: MEASURE_1
(I) SESSION
1
2
3
4
5
(J) SESSION
2
3
4
5
1
3
4
5
1
2
4
5
1
2
3
5
1
2
3
4
Mean
Difference
(I-J)
Std. Error
-10.300
10.444
42.217
8.926
43.553
16.581
15.250
7.388
10.300
10.444
52.517*
6.042
53.853
21.075
25.550
15.055
-42.217
8.926
-52.517*
6.042
1.337
16.299
-26.967
11.116
-43.553
16.581
-53.853
21.075
-1.337
16.299
-28.303
11.387
-15.250
7.388
-25.550
15.055
26.967
11.116
28.303
11.387
*. The mean difference is significant at the .05 level.
a. Adjustment for multiple comparisons: Bonferroni.
a
Sig .
1.000
.052
.467
.939
1.000
.003
.509
1.000
.052
.003
1.000
.597
.467
.509
1.000
.555
.939
1.000
.597
.555
95% Confidence Interval for
a
Difference
Lower Bound
Upper Bound
-60.152
39.552
-.391
84.825
-35.595
122.702
-20.015
50.515
-39.552
60.152
23.678
81.355
-46.745
154.452
-46.313
97.413
-84.825
.391
-81.355
-23.678
-76.466
79.140
-80.026
26.093
-122.702
35.595
-154.452
46.745
-79.140
76.466
-82.656
26.049
-50.515
20.015
-97.413
46.313
-26.093
80.026
-26.049
82.656
Q1: Summary of Results





ANOVA: significant differences between
sessions for only some words
Post-hoc: significant differences between
session means were few
and no pattern of increase/decrease in
differences across sessions
Results were similar for VDUR, BRDUR,
Fricative SM1, the other words, both
speakers
Results were also similar in 2nd experiment
Q1: Summary of Results

No change across sessions = no effect
(practice/fatigue) of multiple productions

Also, no. of repetitions in Exp 2 > Exp 1, yet
no effect of increased repetition on speech
production
Implication of Results

method of eliciting multiple production may
not confound investigation of nature of
speech disorder

but for treatment – practice of this type
elicited in this study may not contribute to
improvement in speech production
Q2: Other Speech Production
Features

Pre-voicing (HO)
Pre-voicing
Figure 1a
Figure 1b
Example: Bug
Q2: Other Speech Production
Features

Pre-voicing (HO)
– voicing preceding release
of word initial /b/ & /d/

Impaired laryngeal control
– difficulty coordinating
timing of stop release for
voiced stops
Word
Occurrence
Bed
83%
Big
52%
Buck
95%
Bug
89%
Dark
52%
Duck
63%
Q2: Other Speech Production
Features
Schwa

Schwa
appended to
final stop
(HO)
Example: Pad
Figure 3
Q2: Other Speech Production
Features


Schwa appended to word-final stop (HO)
– Voiced stops
Indicative of careful
speech production
 Or due to speech
disorder
 Or due to hearing loss
Word
Occurrence
/d/ in “Bed”
93%
/d/ in “Pad”
44%
/g/ in “Big”
86%
/g/ in “Bug”
77%
/g/ in “Pig”
53%
Q2: Other Speech Production
Features - Summary

No pattern in occurrence of these features
over sessions
 Not an effect of multiple production
 May just be characteristic of disordered
speech production
Future Directions
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
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Word-final consonants (stops)
Nasal consonants
Co-articulation
Analysis of the other speech production
features
Analysis of control data
Thank you for listening
