Before any bodily movement can occur, the brain must create a motor
program to determine when and how the appropriate muscles are to be
activated. The same is true for speech. A process of neuromotor
tuning takes place during the split second before normal speech,
preparing the speech mechanism to perform the activities that will be
required. The preparation for phonation also includes a process called
prephonatory tuning. This adjusts the tension of the vocal folds, so
they will be ready to vibrate at the right pitch as the airflow passes
between them. Scientific studies have found that prephonatory tuning
occurs from about one‑half a second to 1/20th of a second before phonation
now appears that Valsalva-stuttering blocks occur because the brain has
not supplied the neurological motor program for the larynx to phonate the
vowel sound for a specific word or syllable. Instead, the brain
has substituted the neurological motor program for effort closure
(which is the
larynx’s function in the performance of Valsalva maneuvers).
for example, the name “Peter?(represented in the phonetic alphabet as /'pi
Before Peter can say his name, his brain must neurologically program the
muscles of his mouth and larynx to make the necessary movements and to
bring his vocal folds together at the right time and with the right amount
of tension to say the vowel. But, because Peter anticipates that saying
his name will be difficult, his brain decides to insert a motor program
for exerting extra effort. So, instead of preparing the larynx to phonate
the vowel sound “ee?(/i/) in “Peter,?the brain instructs the larynx to
do effort closure. The vowel portion of a word or syllable is the
natural place to insert the motor program for effort, because that is the
place in a syllable that usually is loudest and has the most energy.
motor program for “Peter?should have
phonation on the “ee?(/i/)
and the “er?(/d/),
which could be represented like this:
Instead, the brain sends a
motor program containing effort closure where the “ee?should be, which we
will represent like this:
the speaker, the word or name feels as if it contains a “brick wall?that
requires effort to break through. As a result, the speaker may become
fixated on the articulation that precedes the missing vowel sound ?
either repeating or prolonging it or exerting force on it. The speaker
may try to force through the block by building up air pressure, as in a
Valsalva maneuver. The lips, tongue, or larynx may press tightly to block
the upper airway, while the chest and abdominal muscles squeeze to exert
pressure on the lungs. The muscles of the Valsalva mechanism are
neurologically coordinated to build up air pressure; therefore, the
greater the air pressure, the greater the blockage becomes. While this
effort may instinctively feel like the right thing to do, it
actually strengthens the block and makes phonation of the vowel sound even
In Peter’s case, the resulting
forceful blockage of air by the lips might be represented like this:
Peter’s repetition of the initial consonant might be represented like
the initial consonant is repeated during stuttering, it is usually
followed by a neutral vowel sound, “uh?(/c/),
which is called the schwa. This is simply the sound of a grunt,
rather than the vowel that properly belongs in the word or syllable.
To the speaker, it seems as if the initial sound is causing the
block. Therefore, Peter may believe that he blocks on the “p?sound ?
when actually he was making the “p?perfectly well. His real problem was
his inability to move on to the vowel sound that followed it.
When the beginning
consonants do not completely block airflow, such as fricatives,
liquids, and nasals, the result may be a prolongation of
the sound, such as:
Blockages may occur in either the mouth or the larynx,
usually depending on where articulation occurred prior to the missing
vowel. Because the
“h?sound is produced by partial closure of the larynx, blockages that
focus on that sound may also involve laryngeal closure.
It should be noted that the
difficulty in phonation is usually limited to a specific vowel sound
in a specific word or syllable. Therefore, the larynx may be able to make
prolonged phonation on initial voiced consonants like “r?or “m,?but
not be able to phonate the subsequent vowel sound.
In words that start
with vowels (e.g., “apple?, the block may focus on the
laryngeal closure or “glottal stop?(/?/span>/)
that commonly occurs just before the vowel when the speaker does a
“hard onset.?nbsp; This kind of repetition or block could be represented as
This fixation on the initial
sounds creates the false impression that these sounds are causing the
speaker to block, when the real problem is the speaker’s inability to move
on to the vowel sound that follows. The speaker may come to anticipate
difficulty in saying words that begin with certain sounds. This
anticipation will reinforce the brain’s tendency to substitute the motor
program for effort in an attempt to “force out?the feared words. The
speaker may also try to avoid, delay, or hide the blocks by interjecting
extraneous words or sounds as “starters?(e.g., “um,?“you know,??/span>?/span>uh-?/span>uh-?/span>uh-?/span>uh?
or by substituting words that he or she feels will be easier to say.
Persons who stutter may also resort to a variety of other behaviors in
their struggle to force out words.
The intensity of the
speaker’s urge to exert effort may vary, depending on the word or the
speaking situation. Therefore, some blocks may be relatively brief, such
t r OR P---
other instances, the block may go on indefinitely. Or it may continue
until the muscles blocking the upper airway tire out. Nevertheless,
any amount of excessive effort is likely to disrupt fluency.
Valsalva Control Therapy
employs a variety of speaking exercises and psychological approaches that
are designed to reduce these types of stuttering blocks.
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Copyright ?2011 by William D. Parry