hehe, drago mi je Shape of Despair da si se javio. Dodji na naš portal, pa ćemo razmjeniti iskustva. Kao što reče van Riper "..čovjek će najbolje sam sebi pomoći. Svi doktori svijeta ne mogu mu izliječiti mucanje, ako nije spreman za to..."
Vezano za audiološko procesuiranje, evo šta vhrunski stručnjak - defektolog prof. dr. David Ward kaže o tome....malo je duži tekst, ali ne može se naći na internetu, a ova knjiga na amazon-u košta 120 KM.
. Izinjavam se što je tekst ružno prelomljen - PDF format je kriv
"Stuttering and auditory processing
Introduction
It is a matter of interest, and potentially considerable clinical significance,
that the only population with a reduced prevalence of stuttering is the hearing impaired.
Relatedly, one of the most widely researched areas of stuttering in the latter half of the
twentieth century has been the relationship between tuttering and auditory processing,
and attempting to discover processing differences between those who stutter and those who do not.
Findings have led some researchers to argue that stuttering may be related to perceptual, in
addition to production, elements. In this chapter we discuss a number of
different perspectives on the subject and consider the possibility that stuttering
is a disorder of perception rather than production. We have already seen
in chapter 2 that stuttering has been associated with differences in hemispheric
processing of speech and language, and we will consider the evidence
that there are functional neurological differences amongst those who stutter
relating to the processing of auditory information.
Stuttering and the hearing impaired
There is evidence klix back almost a century that stuttering is less prevalent
among the deaf and hearing impaired than in the general population
(e.g., Bleumel, 1913). Backus (1938) found that out of nearly 14,000 deaf
or hearing impaired people contacted through schools of the deaf, only
55 or 0.4 percent stuttered. Harms and Malone (1939) found that only 42
out of 14,458 hearing impaired people also stuttered, which represents
0.29 percent of that population, and is significantly lower than the generally
quoted prevalence figures of around 1 percent amongst the general population.
However, not all studies have supported these findings (Brown,
Sambrooks, & MacCulloch, 1975; Gregory, 1964), whilst Ingham (1984)
speculated that the figures reported by Harms and Malone could relate to
the very high incidence of childhood diseases prevalent at the time of their
study.
Where a decreased prevalence of stuttering among the deaf has been
found, a number of theories have been argued to account for the findings.
Webster and Lubker (1968) believed that the blocking of air conduction
was responsible, much in the way that masking of air conducted feedback
through white noise has been found to produce similar effects amongst some
people who stutter (a phenomenon we will come to below). Some believed,
on the other hand, that the hearing impaired modified their speech in much
the same way that some people who stutter do in attempts to reduce disfluencies
(Wingate, 1970, 1976). This results in a slower rate of speech and
extended phonation, both of which have been associated with the type of
speech that results from delaying the speaker’s auditory feedback (see below).
Both slower speech and extended phonation are commonly used as therapeutic
strategies in fluency shaping approaches to stuttering (see chapters 11
and 12).
Stuttering and altered auditory feedback
One enduring area of investigation into the auditory processing capabilities
of people who stutter has been in the field of altered auditory feedback
(AAF), and the influence of such studies has been considerable both theoretically
and therapeutically. We discuss therapeutic aspects of altered feedback
in chapter 14, but here focus more on the impact altered feedback has
made from an aetiological perspective. There are a number of ways in which
fluency can be improved by altering the way in which the speaker hears his
speech signal. We can discuss these in turn.
Choral and unison speech
Choral or unison speech occurs when a person who stutters either reads
aloud or speaks spontaneously in time with a model speaker (or speakers).
The fluency enhancing effect of this can be dramatic, in many cases bringing
about immediate and normal sounding fluency. In this form, the phenomenon
has limited use therapeutically because there is almost no carryover of
the effect once the accompanying speaker fades their voice out, but it can
be very effective when allied to technology that allows one to hear one’s
own speech output at a different pitch, thus mimicking the choral speech
effect or with delayed feedback.
A variety of early explanations have been launched to explain the effect of
choral speech, including distraction (Barber, 1940), reduced meaningfulness
(Eisenson & Wells, 1942), slower rate and increased loudness (Wingate, 1969,
1976). Lee (1951) argued that the normal speech signal given by the model
speaker could help the person who stutters organize the motor plan for the
upcoming word, yet it may not be the speech signal per se that is the significant
factor. Kalinowski, Stuart, Rastatter, Snyder, and Dayalu (2000) found
that subjects who watched a model speaker silently mouth a text in unison
alongside them brought about an 80 percent increase in fluency, in the absence
of any auditory stimulus itself. The implication of this finding is that
a visual linguistic cue is sufficient to stimulate the auditory cortex. An alternative
notion posits that the model speaker, rather than providing a nondistorted
motor template for the person who stutters to match, instead provides
a pacing or rhythmic one (Johnson & Rosen, 1937); a perspective that would
appear consistent with Kalinowski et al’s findings. It is worth noting that all
of those mentioned above have also been levelled at the fluency enhancing
properties of delayed auditory feedback (DAF), which we discuss below. (The
relationship between choral speech and DAF is an important one, and we
return to this with regard to therapy in chapter 14.)
Shadowed speech
This is a type of cued speech which is very closely related to choral and
unison versions. Technically, shadowed speech occurs where there is a slight
delay between the speech of the model speaker and the person who stutters,
as opposed to the simultaneous output produced during unison and choral
speech. The difference is that while with choral speech the speaker knows
exactly what the model speaker is going to say, shadowed speech can be used
to follow the novel speech of the model speaker. Like choral/unison speech,
shadowing can produce dramatic results (Cherry & Sayers, 1956; Kelham &
McHale, 1966), but like them the gains in fluency tend to be lost once the
stimulus of the model speaker has ended. Because of this, the use of choral
or shadowed speech is now rare, and usually confined only to moments in
therapy or assessment, where it is considered important to have the client
experience a moment of fluency, albeit in the knowledge that this method of
producing it will not provide any basis for sustainable improvement. What is
interesting from our present perspective, however, is the potential relationship
between shadowed speech and delayed auditory feedback. As we will see in
chapter 16, the fluency enhancing effect of shadowed and choral speech has
been put to use in devices which use DAF and frequency auditory feedback
(FAF) to approximate the effects of speaking alongside other speakers.
Delayed auditory feedback
It is now over 40 years since Goldiamond and colleagues first stumbled on the
potential fluency enhancing effects of delayed auditory feedback (Flanagan,
Goldiamond, & Azrin, 1958, 1959; Goldiamond, 1965). Findings from the
earliest experiments centred around the vicarious discovery that some people
who stuttered experienced improved fluency when they put on headphones
and heard their speech played back to them with a slight time delay. (Some
readers may already have experienced DAF as an echo effect when speaking
on a poor transcontinental telephone line.) Commonly, DAF also results in
reduced fluency in nonstuttering speakers (Fukawa, Yoshioka, Ozawa, &
Yoshida, 1988; Stuart, Kalinowski, Rastatter, & Lynch, 2002), although Fukawa
et al. observed that people who stutter were significantly more likely
to be affected by DAF than nonstutterers, and that male nonstutterers were
more susceptible to the effect than females. Most noticeably, Goldiamond
(1965) found a tendency for speakers to slow their rate of speech in an effort
to counteract the disruptive influences of the delayed feedback. Particularly,
at around 250 ms delay1 (0.25 of a second) a prolonged speech pattern was
produced, where vowels became disproportionately more stretched than consonants.
The further finding that the extent of the prolonged speech could be
controlled by altering the delay times lead to the development of a number of
“prolonged speech” programs which used DAF in a systematic way to elicit
fluent speech. (See chapter 12 as to how prolonged speech programs have
developed.) During the early stages of therapy, DAF was set to encourage
excessive prolongation, usually around 250 ms. When clients were able to
demonstrate 100 percent fluency in their speech at this delay setting, the next
stepwise decrease in DAF (usually in 50 ms increments) was introduced to
encourage a slightly faster rate of speech. Again, the client learned to control
fluency using decreased prolongation associated with the reduced DAF. The
procedure was then repeated at incrementally reduced delay levels, with
clients having to demonstrate completely fluent speech at each one before
progressing to the next decreased DAF setting. Eventually, the client reached
the point where he was able to maintain fluency without any delay in auditory
feedback (e.g., Curlee & Perkins, 1969, 1973). At this time it was thought that
the fluency enhancing effects of DAF could be explained simply as byproducts
of the slower rate speech that it produced. During the mid-1970s
and through the 1980s there was a lull in DAF research as clinicians looked to
alternative ways of slowing speech for therapy. It was not until the early 1990s
when a resurgence of interest occurred, largely driven by findings that
increased fluency could indeed result under DAF at normal and even fast
rates of speech (e.g., Stuart & Kalinowski, 1996). This finding has led to a
new generation of clinicians and researchers becoming interested in DAF as a
treatment option for stuttering. We examine the more recent applications in
relation to therapy elsewhere (see chapter 14).
Aside from the therapeutic implications, the early findings that DAF could
enhance fluency for at least some people who stutter led to a number of
theories of stuttering, based on the assumption that timing perception is
disturbed.
Masking
Another consistent finding is that people who stutter become more fluent
when their own auditory feedback, presented through headphones, is masked
by external sound, although this effect only becomes significant if the sound level
of the masking noise is sufficient to block out the speaker’s speech
signal. Maraist and Hutton (1957) found their 15 subjects who stuttered
consistently increased their fluency as the loudness of the masking noise
was increased, and there is corroborating evidence from Burke (1969) and
Murray (1969) for these findings. Cherry and Sayers (1956) in a series of
seminal experiments manipulating auditory feedback found a strong fluency
enhancing effect when a pure tone was presented at a level near the threshold
of pain. A key finding was that stuttering decreased significantly when the
subjects only heard lower frequencies (below 500 Hz) as opposed to only
hearing higher frequency sounds (above 500 Hz). This, Cherry and Sayers
argued, demonstrated the differential role of bone conduction, which more
effectively transmits lower frequency sounds, and air conduction which was
assumed to be associated with a broader range of frequencies. In fact, Cherry
and Sayers’ findings of differential effects in stuttering reduction as dependent
on the frequency ranges (high or low) of the masking noise have not been
verified in subsequent experiments (Barr & Carmel, 1968; Conture 1974).
Nonetheless, the masking effect itself seems to be a consistent one and like
DAF and more recently FAF it has found use as a commercially available
fluency aid, most notably through the production of the Edinburgh masker,
marketed in the 1970s and 1980s (see chapter 14).
Despite the general agreement that masking auditory feedback can be an
effective way of reducing moments of stuttering, opinions as to what forces
are responsible for the effect differ widely. Some saw the early findings, particularly
those of Cherry and Sayers, as evidence for an auditory-perception
theory of the disorder. However, findings from a number of early studies have
suggested that increased fluency could be attributed to reparameterization of
vocal strategies under masking, rather than to factors directly relating to
auditory processing. For example (like DAF) masked speech was found to be
associated with slower speech rates and slower syllable durations (Hanley &
Steer, 1949; Ringel & Steer, 1963), greater vocal intensity (Atkinson, 1952;
Garber, Siegel, Pick, & Alcorn, 1976), and increased fundamental frequency
or higher pitch of the voice (Atkinson, 1952; Ringel & Steer, 1963). In other
words, some claimed that the cause for the increase in fluency lay in changes
within the realm of speech production rather than within auditory processing.
Interestingly, slower speech rate, increased loudness and increased pitch
are all features that have been associated with the speech of the hearing
impaired.
Frequency altered feedback
The finding that fluency can be improved when a speaker hears his voice at a
different pitch (fundamental frequency) was originally reported by Howell,
El-Yaniv, and Powell (1987), and subsequently in a number of papers by
Kalinowski, and colleagues (e.g., Kalinowski, Armson, Roland-Mieszowski,
& Stuart, 1993; Kalinowski, Armson, Stuart, Hargrave, & MacLeod, 1995).
This finding has been associated with the chorus effect, where, as noted
above, increased fluency is thought to arise from having external speech signals
provide a type of external speech template, thus tricking the brain into
believing that the speech signal is exogenous, or not self-produced. Note also
that similar claims have been made for the increased fluency often reported
when the speaker adopts a foreign accent, or is acting out a role. Here too the
brain may not be recognizing the speech as the primary “self-produced” one.
There is evidence to suggest that FAF is more effective in reducing stuttering
when used in conjunction with DAF (see chapter 14), and that responses
to FAF in isolation can be quite individualistic. Ingham, Moglia, Frank,
Ingham, and Cordes (1997) in a series of single subject experiments found
one speaker to receive temporary benefit from the technique, whilst another
found no change in fluency. Another showed a minimal improvement in fluency,
but a deterioration in speech quality; a final speaker made significant
and sustained improvement.
Cica Tafro da lijeci mucanje? 