Re: Why do People Stammer or Stutter when they talk ?

Dear Ganesh,

First, I must say that I‘m not a specialist in language problems so my 
knowledge about stuttering is quite limited. One important thing about 
this problem is to differentiate between stuttering and developmental 
dysfluency. In stuttering, the tempo is faster than normal, a vocal 
tension is often apparent and frustration may be present whereas in 
developmental dysfluency, those problems are nearly absent (1). Moreover, 
the duration and frequency of syllable repetition is more important in 
stuttering; developmental dysfluency is usually characterized by 
repetition of whole words rather than syllable.  Since your question is 
about the possible mechanisms underlying stuttering, they are not 
completely known but several hypotheses are proposed. One of them is that 
a neurophysical problem disrupts the precise timing required to produce 
speech (2), which may be hereditary (3, 4). Some problems with auditory 
processing are also probably involved in (at least some forms of) 
stuttering. In a recent activation study (5), comparisons are made between 
people who stutter and some that do not in order to be precise which brain 
regions may operate in a different manner between the two groups. Results 
show that differences exist in the more or less active brain regions 
associated with stuttering. In general, brain regions that seem to be 
implicated in stuttering are the motor regions of the mouth, the frontal 
speech areas (Broca’s area), the insula, some temporal auditory areas and 
the cerebellum. Interestingly, brain areas associated with stuttering 
seem to be located in the right hemisphere (except for the cerebellum) 
although it is well known that the left hemisphere integrity is usually 
crucial for normal language capacities. 

	I don’t know if some differences may exist when a person speaks 
two different languages. If so, I think that the way and moment that the 
second language is acquired as well as the precise nature of stutter 
problem (i.e. developmental, neurological, following vascular accident 
etc…) must be considered. I have look for more precise studies about that 
but I did not find anything.

 I hope that help!

Eric


(1)	Van Riper C. The nature of stuttering. Englewood Cliffs, N.J.: 
Prentice-Hall, 1971:28.
(2)	Guitar BE. Stuttering and stammering. Pediatr Rev 1985;7:163-8.
(3)	Williams DE. Differential diagnosis of disorders of fluency. In: 
Darley FL, Spriestersbach DC, eds. Diagnostic methods in speech pathology. 
2d ed. New York: Harper & Row, 1978:409-38.
(4)	Poulos, MG & Webster, WG. Family history as a basis for 
subgrouping people who stutter. J Speech Hear Res 1991;34:5-10
(5)	Fox, PT et al. Brain correlates of stuttering and syllable 
production. A PET performance-correlation analysis. Brain 2000;123:1985-
2004.

See also :

Grant, AC Stroke-associated stuttering. Arch Neurol 1999;56:624-7.

Lawrence, M & Barclay III, DM. Stuttering: a brief review. Am Fam 
Physician 1998;57:2175-8.

Andrews G et al. Stuttering: a review of research findings and theories 
circa 1982. J Speech Hear Disord 1983;48:226-46.