SPEECH MOTOR CONTROL IN FLUENCY DISORDERS KUNNAMPALLIL GEJO JOHN,MASLP KUNNAMPALLIL GEJO JOHN
Jan 01, 2016
SPEECH MOTOR CONTROL
IN
FLUENCY DISORDERS
KUNNAMPALLIL GEJO
JOHN,MASLP KUNNAMPALLIL GEJO JOHN
• Stuttering can be conceived of as a disorder of speech
motor control.
• There is a motor disturbance which is evident in the
abnormal types and amount of speech dysfluencies.
• There is a complex set of relations between this motor
disturbance, the emotional accompaniments of the
disorders and further alterations in speech behaviors.
KUNNAMPALLIL GEJO JOHN
• Vocal reaction times and manual reaction times of stutterers
was examined and compared with those of nonstutterers
and found a greater difference b/w them (Starkweather,
Franklin and Smigo, 1984).
• This indicated that stutterers had a general motoric deficit
which slowed their reaction time, in addition they had
learned habits of tension and struggle that were specific to
the speech mechanism.
• The presence of this additional muscular tension acted as a
drag on the coordinative structures of speech and slowed the
vocal reaction time even further. KUNNAMPALLIL GEJO JOHN
• Kent 1983, examined the variability of speech segment
durations in stutterers and nonstutterers and found that the
stutterers produced segments that were not more variable in
their duration.
• The presence of a generally raised level of muscle activity
could also be used to explain such a result since the temporal
location of a gesture would be less sure if movements
initiating and terminating the segment were made less
smoothly.
KUNNAMPALLIL GEJO JOHN
• Zimmerman 1980 put forth the idea that stuttering
should be regarded as a disorder of movement.
• He suggested that at the level of the motor neuron a
number of inputs from diverse sources are integrated,
and the sum of these inputs determines the
background tonus and triggering thresholds for
coordinated structures
KUNNAMPALLIL GEJO JOHN
Characteristics of stuttering as
a motor control disorder
• Speech initiation problems both in conversational
speech and in formal reaction time testing.
• Initiation difficulties are not due to slowed neural
conduction time but due to problems with
coordinating and timing movement (Harbison,
Porter and Tobey, 1989) which is typical of many
motor control disorders (Ludlow and Connor,
1987).
KUNNAMPALLIL GEJO JOHN
Involuntary, abnormal or excessive muscle activation
patterns occur during speech oscillations in
stuttering.
These can be rhythmic oscillations involving several
muscles with a frequency range of 5 – 12 Hz
(McClean, Goldsmith and Cerf, 1984) heightened
muscle activity (Freeman and Ushijama 1978) or
absence of the expected muscle activity (McClean
1984).
KUNNAMPALLIL GEJO JOHN
• Stuttering is a task specific disorder; these patients
have no clinical evidence of difficulties with other
vocal tract actions such as chewing, swallowing,
eating or singing
• Stuttering seems to appear only when the speaker
becomes a more fluent speaker of a language
• Stuttering is exacerbated by stress. Particular situations
and listeners seem to trigger stress, affecting stuttering
severity.
KUNNAMPALLIL GEJO JOHN
• Stuttering is a focal disorder, affecting only
certain structures or movements of vocal tract
like in dysarthria and dystonias.
• Stutterers speech dysfluencies increases with
increased constraints on performance, which is
typical of most movement disorders
(Parkinsonism).
• Stuttering improves with practice like other
motor disorders.
KUNNAMPALLIL GEJO JOHN
MODELS OF SMC IN FLUENCY
DISORDERS
1. MacKay‟s Model
BUFFER DISPLAY
INDIVIDUAL PHONEME
LEVEL
CONTEXTUAL INTEGRATION
MOTOR UNITS
KUNNAMPALLIL GEJO JOHN
• The model is composed of a buffer system which displays
phonetic units in abstract forms but in correct serial
order. This may be equated to conceptual level.
• This is fed into an individual phoneme level partially
activating or priming a set of singly represented
phonemic units which are unordered.
• The buffer also generates a set of programs for modifying
the phonemes according to contextual constraints. This
may be equated to encoding process.
KUNNAMPALLIL GEJO JOHN
• These levels are then fed into a motor unit level, where the
contextual variants are coded
• A “scanner” which sweeps over the motor variants in the
motor unit level in a unidirectional manner at a voluntarily
determined rate.
• When a partially primed unit is passed by the scanner, it
receives an added boost of excitation, bringing it to
threshold for a series of motor commands to be sent to the
speech musculature.
• This is then carried out, which becomes the speech output. KUNNAMPALLIL GEJO JOHN
KUNNAMPALLIL GEJO JOHN
MODEL 1(NS) MODEL 2(S)
MODEL 3(S) MODEL 4(S) KUNNAMPALLIL GEJO JOHN
• For the NS, hyperexcitability of motor units following their
activation is not sufficient to exceed the motor unit
threshold for stuttering (MODEL 1) yet, stressed units
come closer to threshold than unstressed units
• In stutterers, (a) the same preprimed levels for stressed and
unstressed units as normal, but a lowered motor unit
threshold (MODEL 3)
(b) Greater levels of hyperexcitability than normal (M 2)
(c) Greater prepriming for stressed units, but normal thresholds
and excitability boosts (M 4)
KUNNAMPALLIL GEJO JOHN
PROLONGATION:
• Individual features may interact in a mutually inhibitory
way e.g. the lip movements for /p/ may be stuttered silently
with neither airflow nor phonation, as if the motor units for
phonation were inhibited, while those for lip movement
were in a state of oscillation
• If oscillations between contradictory elements were rapid
enough, fusion might appear, thus lengthening the speech
sound (i.e.) If the time of triggering is longer, then the
speech sounds may be prolonged.
KUNNAMPALLIL GEJO JOHN
MASKED OR OMITTED:
– It depends on the time required for a unit to reach threshold and the rate of scanning.
• Let us assume that 2 units, the 1st unstressed and the 2nd stressed, are passed over by the scanner. The 1st will be omitted if the time required for it to reach threshold is greater than the time required for the scanner to activate the 2nd unit and for it to reach threshold. But sweeping rate of the scanner is voluntary and determines the speaking rate.
• If swept rapidly, omission is likely to occur, otherwise there is no omission.
KUNNAMPALLIL GEJO JOHN
• Blocks:
– When there are omissions, stutterers generally
closely monitor their speech, so to overcome this,
he simply stops when a planned phoneme does
not materialize.
KUNNAMPALLIL GEJO JOHN
2. THE NEUROSCIENCE MODEL:
(Nudelman et al, 1992)
• The neuroscience model proposes that stuttering is caused by
instability in speech motor control.
• Specifically, a stuttered event is viewed as consisting of two
components :
(1) a momentary instability (in the control theory sense) in the
speech motor control system.
(2) the system‟s response (including its corrections) to this
instability. KUNNAMPALLIL GEJO JOHN
• According to this model, the instability of the
speech control system that leads to stuttering
depends on the interaction of the two nested
functional loops:
1. an outer cognitive loop that provides the reasoning
behind and choice of the words being said
2. an inner production loop that programs and
monitors the sounds being made.
KUNNAMPALLIL GEJO JOHN
• This model provides two possible reasons why the speech
systems of people who stutter are more likely to become
unstable than those of normally fluent speakers:
1. more processing time may be needed by the outer loop,
2. phase margins in the inner loop may be smaller.
The phase margin is, in effect, the margin of error.
In general, stuttering occurs when there is mismatch between
the selection and programming of speech sounds and the
production of these sounds. It is a causal theory
KUNNAMPALLIL GEJO JOHN
Background and Development:
• The model draws on a reductionist or “top – down” model of motor
control, which is described in terms of “Functional loops”
(Nudelman et al.,1989).
• Functional loops underpin the four stages of speech production:
Ideation, linguistic programming, motor programming and motor
output.
• They presumably involve the “ temporally overlapping, parallel
execution of the stages with feedback”.
• Functional control loops perform functions that hypothetically must
be accomplished before the desired motor behavior occurs.
KUNNAMPALLIL GEJO JOHN
• vocal tracking tasks in which adult who stutter and control
subjects tracking computer – generated frequency –
modulated sound waves by humming.
• The stutters responded as quickly as the control subjects to
changes in frequency, but needed more time for processing
the change in tracking frequency.
• The stutters were more variable in terms of phase shift and
so, it was concluded, were more likely to develop momentary
instabilities
KUNNAMPALLIL GEJO JOHN
• The parameters of the functional loops fluctuate widely and continuously: consequently mistiming occurs intermittently.
• This explains the natural variability of stuttering within individuals; namely why people do not stutter on every word or syllable and why stuttering varies over time.
• Factors that may influence processing time in the outer loop may be psychological, linguistic or sociologic.
• Factors in the inner loop that can increase the risk of breakdown are a function of “ motor context”, namely the position and tension of articulators and the complexity of articulatory movements.
KUNNAMPALLIL GEJO JOHN
• The model predicts that fluency can be enhanced into two ways:
1. By increasing the phase margin in the outer loops. This can be done directly by “ making a therapeutic strategy automatic”, and indirectly by the person adopting a speech pattern that “slows, rounds, or smoothly shapes the movements”.
2. By decreasing the amount of processing time required by the inner loop, for example by practice and these are the sorts of strategies used by SLP‟s in fluency – shaping treatments.
KUNNAMPALLIL GEJO JOHN
• Foundas et al, 2001 suggested that their findings of
structure abnormalities in the brains of adults who stutter
lend support to the neuroscience model.
• They suggested that the anomalies they identified, which
were in the perisylvian speech – language areas, could cause
stuttering by reducing the efficiency of neural processing in
the outer loop referred to in the neuroscience model.
KUNNAMPALLIL GEJO JOHN
EXPLAN MODEL:
Howel 2004
• EXPLAN is an autonomous model of the production of the spontaneous speech that applies to speakers who stutter and fluent speakers.
• Planning (PLAN) and execution (EX) are independent process that reflects the linguistic and motor levels, respectively.
• Failures in the normal mode of interaction between the PLAN and EX processes can lead to fluency failures when plans are too late in being supplied to the motor systems
KUNNAMPALLIL GEJO JOHN
• The EXPLAN model (Howell, 2004) argues that speech
production involves independent planning and execution
processes.
• Fluency failures such as repetition of prior words, pausing,
prolongation and repetition of parts of the current word
occur when the word to be produced is not ready (the
planning process is not complete) by the time the execution
of the previous word is concluded.
• EXPLAN can explain the behaviour of both fluent speakers
and also the speech of speakers who stutter (SWS).
KUNNAMPALLIL GEJO JOHN
• The independence of planning and execution systems
allows the plan for a future segment to be generated
during the time the plan for current segment is being
executed.
• If execution time is long enough, the plan for the
following word will be ready after execution of
present word has been completed; and is executed in
sequence
KUNNAMPALLIL GEJO JOHN
• Fluency fails when a speaker has finished execution
of one plan and next one is not ready for execution.
There are 2 Main reasons why this arises.
1. The inherent properties of linguistic segments make
their planning slow (difficult)
2. Speech is executed at a high rate. The role of each of
the factors can be appreciated by examining the fig.
KUNNAMPALLIL GEJO JOHN
Plan (n) Plan (n*1) Plan (n*2)
Ex (n) Ex (n*1)
fig 1 fig 2
Difficulty increases the planning time of following word beyond time needed to execute the current word.
Increasing execution rate has effect of shortening the planning time allowed for following word.
KUNNAMPALLIL GEJO JOHN
Adaptive model theory (AMT)
Megan D Neilson & Peter D Neilson
• The AMT of motor control is a general formulation of the interactions between the sensory and motor processes underlying purposive control of movement.
• Skilled movement is generated with reference to an internal store of information established by integration of sensory feedback with the motor activity which produced it.
• AMT addresses the mechanisms by which sensorimotor relationships might feasibly be established, maintained, refined and whenever necessary, adaptively modified.
KUNNAMPALLIL GEJO JOHN
• According to AMT any system responsible for voluntary motor
behavior can be conceptualized as a controlled dynamic system
driven by an adaptive controller.
• The controller has the task of transforming a preplanned desired
sensory trajectory into set of motor commands, which when passed
through the controlled system will produce the required sensory event
• Establishing and adaptively maintaining a multivariable, nonlinear,
time varying sensorimotor model requires many network modules
operating as a distributed parallel processor.
• It follows that the greater the modular resources available for the
task, the faster and/or more precisely a model can be determined
KUNNAMPALLIL GEJO JOHN
• The implications of AMT for stuttering stem from this
neural resources conceptualization.
• That stutterers lack response for efficient sensorimotor
modeling is strongly suggested by the finding that stutterers
perform poorly on auditory tracking tasks, given that the
problem of transforming a body movement into the variation
of an auditory tracking marker closely parallels the problem
of transforming a changing VT configuration into a
changing speech signal
KUNNAMPALLIL GEJO JOHN
• The authors therefore, suggest that stutterers are deficient
in the processing resources normally responsible for
determining and adaptively maintaining the adaptive
models which sub serve speech production.
• As a consequence of this deficiency, the stutterer must spend
longer in evaluating the sensorimotor relationships involved
in speech, evaluate them less precisely, or deploy additional
resources at the expense of other concurrent functions
KUNNAMPALLIL GEJO JOHN
• Because the availability and efficiency of resources
are affected by factors such as task familiarity,
competing cognitive workload, motivation and
arousal, the proposed framework predicts variation of
fluency with changing circumstances of capacity and
demand.
KUNNAMPALLIL GEJO JOHN
Assessment of stuttering:
Aspects of stuttering to be assessed:
1. The effects of sensory set, different speaking situations on eliciting stuttering.
2. The effects of motor set, speaking tasks on eliciting stuttering.
3. The effects of motor response patterns, speech targets on eliciting stuttering.
4. Changes in psychophysioloigcal set during episodic periods of marked fluency and non fluency
5. The effects of feedback elimination or enhancement of eliciting stuttering.
KUNNAMPALLIL GEJO JOHN
How do we assess these?
To assess these we should first of all have knowledge about:
1. Severity of stuttering: consider secondaries and speech
behaviors
2. Effects of speaking situation of moments of stuttering
3. Effects of speech tasks or loci of stuttering.
Knowing these, we have to assess the effects of speech targets (i.e.)
to determine which motor response patterns are most affected
by stuttering, an analysis is needed of disfluent behavior
during particular speech targets.
KUNNAMPALLIL GEJO JOHN
• When measuring, the percentage time disfluent in various
speech situations and tasks, an inventory of the gestures
observed during stuttering should determine, which
structures and muscles should be studied during physiologic
and acoustic analysis of stuttering.
Methods to study:
1.Movement transduction:
• This needed to study movement abnormality. i.e. either
tremor, an absence of movement or incorrect or abnormally
slow or fast movement.
KUNNAMPALLIL GEJO JOHN
• Transducers useful for clinical and experimental
measurement of movement by vocal tract structure are
shown in the table below:
• Structure Clinical Experimental
1. Abdomen and Magneto Respitrace
chest wall meter
2. Larynx Pizeoelectric Fiberoptic video
sensor, EGG palatography
3. Lips and jaw Pizeoelectric strain guage
sensor
4. Tongue Articulograph Ultra sound
KUNNAMPALLIL GEJO JOHN
Assessment of:
a) Respiration: Here we do not assess the amount of air volume
the subject uses but rather the timing of the chest wall and
abdominal movement and their coordination during
breathing.
b) Laryngeal movement: EGG can be used to identify VF
adduction and glottal vibration. But it cannot identify the
tremor when VF are in abducted position or during whisper.
So piezoelectric accelerometer can be used
KUNNAMPALLIL GEJO JOHN
• Lips and Jaw: Here the intention is to measure the displacement degree, tremor, identifying irregularity or absence of movement and to measure movement time (from the onset to the completion of a gesture) Pizeoelectric sensor can be used
• Tongue movement: Here changes in tongue shape is measured using ultrasound palatography. It involves placing of electrodes over the palate which has sensors to detect tongue contact. This method alters sensation in the mouth and changes oral shape, both of which are unacceptable for the study of SMC.
KUNNAMPALLIL GEJO JOHN
From all the above, we can measure:
• Number of tremor oscillations / time
• the time of initiation and completion of movement
• Coordination between different movements and
structures and
• the movement duration
KUNNAMPALLIL GEJO JOHN
2. Muscle activation:
Which muscles are involved in dysfluent behaviors?
• EMG can be used to study muscle activation for
examining which muscles are involved in disfluent
behaviors. This is to determine whether biofeedback
training might be useful or not.
KUNNAMPALLIL GEJO JOHN
Muscle activation during disfluency may vary from
hypertonicity, abnormal muscle activity patterning or an
absence of activity. This may be helpful in determining
whether reducing activation in particular group of muscles
will be beneficial for that speaker.
EMG measures: It can be done using a surface electrode or
hooked electrode (indwelling wired electrodes).
• Measures of muscle activation must be relative to the mean
amount of muscle activity during similar movement patterns
which do not involve disfluent speech.
KUNNAMPALLIL GEJO JOHN
Compare muscle activity with same movement but with disfluent speech.
– Then increases in muscle activation 200% greater than mean – muscle is abnormally active
– A decrease in activation in 50% below the mean – muscle is abnormally quiet.
– Regular repetitive bursts during disfluency – tremor
– Prolonged burst – dystonic posturing
• Experience and familiarity with normal patterns during speech are needed to identify abnormal patterns
KUNNAMPALLIL GEJO JOHN
ACOUSTIC MEASURES:
Spectrography is used to measure:
• Speech timing: execution time for syllables, the pause time
between syllables, syllable repetition rate – describe timing
abnormalities
• Duration of disfluency, rate of syllable or sound repetition,
breaks in phonation
• F0 and 1st harmonics to examine voicing changes
• Formant frequencies, transitions, fluctuations, vowel durations
KUNNAMPALLIL GEJO JOHN
• Recent acoustic studies have continued to identify
unusual vocal behavior characteristics among stutterers.
• On interesting pattern of finding concerns the
fundamental frequency of their pitch.
• Two studies (Adams, sears and Raming, 1982; Ramig
and Adams, 1981) showed the restricting fundamental
range by either monotone or high and low pitched oral
reading may reduce stuttering.
KUNNAMPALLIL GEJO JOHN
• Even without such manipulations there is evidence that
adult stutterers probably use a relatively restricted
fundamental frequency range (Healey, 1982)..
• Also the formant frequencies of adult stutterers show
relatively little variation, even during changes in their
frequencies of „dysfluencies‟, oral reading rate and vowel
durations under fluency inducing conditions
KUNNAMPALLIL GEJO JOHN
• It has been found that voice onset & offset actions in
oral reading may partially influence stuttering ( Adams
and Reis,1971,1974), but these findings was not
replicated when young stutterers performed similar oral
readings (McGee, Hutchinson and Depty,1981).
• Also findings of slow voice initiation and termination
among stutterers (Adam and hyden, 1976) appear to be
conditioned by subject age and the severity of stuttering
factors.
KUNNAMPALLIL GEJO JOHN
• Nevertheless a careful analysis of the speech of the young
stutterers (Wall, Stark weather, and Harris,1981) has
shown that majority of their stutterings occur when a
voice onset is required after a pause; regardless of its
location in a sentence.
• The simplest interpretation of these findings is that
voice timing problems may initially surround stuttering
events, but, with time, they spread to the rest of a
stutterer‟s speech.
KUNNAMPALLIL GEJO JOHN
• Acoustic analysis have been widely used to indirectly
assess both the temporal (e.g., Healy and Gutkin, 1984;
stark weather, Hirschman and Tannentaun, 1976) and
spatial (e.g. klich and May 1982; Pindzola, 1986)
characteristic of stutterers fluent speech.
• Recent acoustic studies lend support to the findings of
aberrant temporal characteristics without similar
aberration in spatial characteristics during stutterer‟s
fluent speech movements.
KUNNAMPALLIL GEJO JOHN
Acoustic and articulatory research
• Direct articulatory measurements cause so much discomfort to
patients and are so difficult to perform the alternative indirect
measurements based on the acoustic signal would be very
attractive, if they would give equivalent information.
• The success of the acoustic theory of speech production in
predicting acoustic patterns from articulatory shapes suggest
that the inverse operation, where articulatory movements are
estimated from acoustic measurements should be viable.
KUNNAMPALLIL GEJO JOHN
• However, the relation between acoustic patterns and articulatory
configurations proves to be far from being one to one (because in
general the dimensionality of the articulatory space is much
larger than that in the acoustic domain).
• To some extent this can be obtained by the dynamic programming
procedures applied to dynamic articulatory gestures.
• Thus sophisticated modeling techniques are necessary in order to
make reliable inferences about articulation from acoustic
measurements.
KUNNAMPALLIL GEJO JOHN
KUNNAMPALLIL GEJO JOHN
Babol
Basu
(1979)
5 persons
with &
without
stuttering
( age and
sex
matched )
age 15 to
20 yrs
A passage in
kannada which
had words with
plosives /p/, /t/,
/k/, /b/,/t/ and
/g/ in word initial
position. CV
syllables where „k‟
was a plosive and
„u‟ was the vowel
a wide band
spectrographic
analysis was done
CV syllables revealed
longer VOT,s in persons
with stuttering.
Voicing lag for unvoiced
plosives and voicing lead
for voiced plosives in
both groups.
In normals VOT
increased as the
articulator moved
backwards in the oral
cavity which was not
observed in persons with
stuttering. KUNNAMPALLIL GEJO JOHN
RC perumal
(2001
15 normal and
stuttering
children (6 to
9yrs)
3 age groups
were included(
1yr gap)
Task:
phonation and
termination of
/a/ on hearing
auditory
stimuli
No significant
difference
between voice
initiation time
(VIT) and
voice
termination
time (VTT)
within each
group.
KUNNAMPALLIL GEJO JOHN
MV
Rames
h
(1983)
4
kannada
speaking
stutterers
and non-
stutterers
( age, sex
and
reading
proficienc
y matched
Material; 2 non
emotional and
meaningful kannada
passage, with equal
number of syllables.
Conditions (1) DAF
(2)NAF (normal0-
duration of delay of
200msec
Measures VOT
vowel duration,
vocal intensity and
Fo, rate of speech
and syllables
Normals manifested
stuttering like behavior under
DAF whereas stutterers
showed a reduction in
dysfluencies
Rate of speech decreased in
both groups under DAF Fo
increased in normals but no
change in stutterers
VOT decreased in stutterers
Vocal intensity increased in
normals KUNNAMPALLIL GEJO JOHN
Suchitra
Sridhar
(1991)
Swapna
Sebastia
n (1997)
10 normals
and 10
stutterers (
age 15 to
20)
5 normals
and
stuttering
adults ( 15
to 25yrs)
Exp 1: task
reading
„rainbow‟
passage,
Exp 2: read „pa‟
„ta‟ „ka‟
Read an „all
voiced‟ and a
combined
passage‟
Speech and
laryngeal output
were recorded
Reduction in VOT
frequency of
stutteringSIT,STT in post
therapy reduced.
Differences in Fo, voice
onset time, word duration
and vowel duration
No differences in formant
frequencies
KUNNAMPALLIL GEJO JOHN
JFD 28, 2003 pg: 273 – 295
STUTTERING : A DYNAMIC MOTOR CONTROL DISORDER
Christy L. Ludlow, Torrey Loucks
• The purpose of this review article is to determine what neural mechanism may be dysfunctional in stuttering
• Three sources of evidence are reviewed:
1. Studies of dynamic inter – relationships among brain regions during normal speech and in persons who stutter suggest that the timing of neural activity in different regions may be abnormal
KUNNAMPALLIL GEJO JOHN
2. The brain lesions associated with acquired stuttering are
reviewed. These indicate that in a high percentage of cases, the
primary speech and language regions are not affected but lesions
involve other structures, which may modulate the primary sp & lg regions
3. To characterize the motor control disorder in stuttering,
similiraties and differences from focal dystonias such as
spasmodic dysphonia and Tourette‟s syndrome are viewed.
These indicate that central control abnormalities in stg are not due
to disturbance in one particular brain region but rather a system
dysfunction that interferes with rapid dynamic speech processing
for production
KUNNAMPALLIL GEJO JOHN
JFD 20, 1995 Pg 157 – 170
SPEECH MOTOR AND LINGUISTIC SKILLS OF YOUNG
STUTTERERS PRIOR TO ONSET
Kloth & Jansen
• Theorist have increasingly suggested that both speech motor and
linguistic factors are involved in the etiology of stuttering.
• This contention has been supported by findings that tend to
indicate that youngsters who stutter have a slower speech rate
and are less linguistically skilled than nonstutterers
• However, no inferences can be drawn from these findings as to
the nature or the causation of this disorder
KUNNAMPALLIL GEJO JOHN
• This is because the a fore mentioned findings might be a result tather than a cause of the disorder.
• In order to clarify the directionality issue, a multi – year prospective study was undertaken that involved 93 preschool children with parental history of stuttering
• At the initial session, none of the high risk children sample was regarded as having a stuttering problem.
• One year later, 26 children were classified as stutterers. Statistical analysis revealed that prior to the onset of stuttering these children did not differ from the other youngsters studied with respect to either their receptive or expressive language abilities
• However, their rate of articulation was significantly faster
KUNNAMPALLIL GEJO JOHN
• The latter finding is taken to mean that the children who developed stuttering were not limited in speech motor ability.
• Rather, their fluency failures are seen as a result of a relatively high articulation rate.
• It is noteworthy, in this regard, that the rate of the high – risk children who continued to be viewed as non stutterers was slower than that previously reported for youngsters of their age.
• This suggests that the slower rate served as a buffer against fluency breakdown
KUNNAMPALLIL GEJO JOHN
JFD 5, 1980 359 – 372
MOTOR PERSEVERATIVE BEHAVIOR IN AFULT SUTTERERS AND NONSTUTTERERS
CHERYL LYNN & COOPER
• The performances of 22 adult stutterers and nonstutterers on motor task requiring the graphic reproduction of a sequence of alternating figures following the production of a series of non alternating figures were studied
• The finding that there were no differences in the performance of the two groups on the alternating motor tasks are interpreted as challenging the validity of previous observations that motor perseverative behavior exists in stutterers and is indicative of a central neurologic deficit in that population
KUNNAMPALLIL GEJO JOHN
JSHD 57, 1993 Pg 504 – 518
MOTORIC AND LINGUISTIC VARIABLES AMONG CHILDREN WHO STUTTER: A FACTOR ANALYSIS
GLYDON D. RILEY & JEANNA RILLEY
• 76 children who stuttered, aged 5 – 12 were administered tests of motor coordination, psycholinguistic abilities, and stuttering severity
• A factor analysis of 19 selected variables yielded four statistically useful factors that implicated linguistic integration, oral motor ability, and auditory processing as underlying components among the same population
• These components are assumed to affect a child‟s severity was not related to any of the four factors.
KUNNAMPALLIL GEJO JOHN
JCD 33, 2000, 391 – 428
RESEARCH ON SPEECH MOTOR CONTROL AND ITS
DISORDERS: A REVIEW AND PROSPECTIVE
RAY D. KENT
• This paper reviews issues in speech motor control and a class of
communication disorders known as motor speech disorders
• Speech motor control refers to the system and strategies that
regulate the production of speech, including the planning and
preparation of movements and the execution of movement plans
to result in muscle contractions and structural displacements
KUNNAMPALLIL GEJO JOHN
• Traditionally, SMC is distinguished form phonologic
operations but in some recent phonologic theories, there is
a deliberated blurring of the boundaries between
phonologic representation and motor functions.
• Moreover, there is continuing discussion in the literature
as to whither a given motor speech disorder, especially
apraxia and stuttering, should be understood at
phonologic level, the motor level or both of these.
KUNNAMPALLIL GEJO JOHN
THANK YOU
KUNNAMPALLIL GEJO JOHN