Chapter VI
Summary and Conclusions
Stuttering has been considered as a disorder of prosody and several authors have tried
to verify this theory. However, most studies have analyzed FO or FO range m
sentences. Although FO range has been measured in a number of studies, the value
represents the FO range of the entire sentence; they don't specifically represent the
pitch range of the nucleus or the boundary tone. Hence, they don't adequately describe
the intonation properties of the sentence. Considering these disadvantages posed by
the analysis of only FO related parameters, the present study analyzed the intonation
of the passage in-depth by following the British system (widely adapted) of intonation
analysis. Thus, the study examined the effect of prolonged speech technique and
modified airflow therapy on intonation in persons with stuttering. Two groups of
subjects participated in the study. Group I consisted of 26 persons with stuttering. The
subjects' age ranged from 15-26 years with a mean age of 20 years. Group II
consisted of 18 age and gender matched normal control subjects. Subjects in group I
were randomly assigned to either prolonged speech technique or modified airflow
therapy. Accordingly 13 subjects each underwent 3-week prolonged speech technique
or modified airflow therapy. Subjects read a 209-word all phoneme reading passage in
Kannada developed by the author before and soon after the therapy. Thus there were
2 conditions (pre- and post-therapy), two groups of PWS - one who underwent
prolonged speech technique and one who underwent modified airflow therapy and one group of normal subjects. All the readings were audio-recorded and used for
perceptual and intonation analyses. Percent and type of dysfluency, syllables per
minute, and naturalness score were measured in pre-and post-therapy reading samples
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and compared with normal subjects. Dysfluent utterances were analyzed as nondiscrepant, discrepant, and absent. Length of the intonation group in terms of syllables
and identification of nucleus was done on each sentence in both conditions and
normal subjects. In addition, FO range, higher FO and types of intonation errors were
identified.
The results revealed several points of interest. First of all a significant difference
between groups on mean percent dysfleuncy was found. The mean percent dysfluency
decreased from pre to post-therapy condition in PWS using prolonged speech
technique, and modified airflow therapy.
However, there was no significant
difference within groups of PWS. There was significant difference between pre- and
post-therapy dysfluencies of PWS and normal subjects. Table 43 shows the mean and
SD of percent dysfluency across conditions and therapy techniques.
Conditions/therapy
technique
Prolonged speech
technique
Modified airflow
therapy
Total
Pre-therapy
Post-therapy
Mean SD
17.48 19.13
Mean SD
1.14 1.71
12.08 9.73
.52
1.23
14.78 15.13
.83
1.49
Norma 1
subjecls
Mean SD
0.00
0.00
Table 43: Mean and SD values of percent dysfluency across conditions and therapy
techniques.
Secondly, all types of dysfluencies decreased from pre- to post-therapy condition. Of
the different types of dysfluencies, syllable repetitions and unfilled pauses were the
most common and inteijections were the least common.
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Thirdly, SPM decreased significantly from pre- to post-therapy condition in PWS who
underwent prolonged speech technique. Also, SPM in PWS in pre- and post-therapy
condition significantly decreased compared to normal subjects. Table 44 shows mean
and SD of rate of reading across conditions and therapy techniques.
Conditions/therapy
technique
Prolonged speech
technique
Modified airflow
therapy
Total
Pre-therapy
Post-therapy
Mean SD
Mean SD
335.42 47.03 302.43 43.68
Normal
subjects
Mean SD
389.11 43.19 353.41 47.45 413.25 44.44
362.27 52.03 327.92 51.7
Table 44: Mean and SD values of rate of reading (SPM) across conditions and therapy
techniques.
Fourth, MNS increased from pre- to post-therapy reading in modified airflow therapy
and prolonged speech technique group, though not significantly. Pre and post-therapy
MNS were significantly lower in PWS compared to normal subjects. Table 45 shows
mean and SD values of MNS across conditions and therapy techniques.
Conditions/therapy
technique
Prolonged speech
technique
Modified airflow
therapy
Total
Pre-therapy
Post-therapy
Mean SD
Mean SD
41.03 47.44 43.59 34.39
Normal
subjects
Mean SD
58.97 43.36 61.54 40.47 100
0.00
50.00 45.46 52.56 37.92
Table 45: Mean and SD values of MNS across conditions and therapy techniques.
Fifth, non-discrepant type of intonation increased in the fluent pre-therapy and posttherapy condition compared to dysfluent pre-therapy condition. Intonation was found
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to be absent only in dysfluent utterances. Table 46 shows percent type of intonation
across three conditions.
Type of
intonation
Absent
Discrepant
Non-discrepant
Conditions
Fluent pretherapy
Dysfluent pretherapy
26.67
22.27
51.11
Posttherapy
-
27.27
72.73
24.24
75.76
Table 46: Percent type of intonation across three conditions.
Sixth, the percent of occurrence of shorter intonation group length (0-5 syllables) was
higher and the percent of occurrence of longer intonation group length (>11 syllables)
was lower in PWS in both conditions compared to normal subjects. Table 47 shows
the percent occurrence of different length of intonation group in the three groups.
Groups
Normal
subjects
Pre-therapy
Post-therapy
0-5
syllables
21.0
39.3
35.6
Length of the intonation group
6-10
11-15
>15
syllables
syllables
syllables
31.57
30.63
16.81
34.45
46.55
19.37
15.39
6.88
2.47
Table 47: Percent of different length of intonation group in 3 groups.
Seventh, the nucleus occurred on similar words in PWS and normal subjects in 14 of
25 sentences in pre-therapy and 15 of 25 sentences in post-therapy condition. That is
56% (pre-therapy) and 60% (post-therapy) of times the nucleus was the same in PWS
and normal subjects. Nucleus was different in PWS compared to normal subjects in
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44% (pre-therapy) and 40% (post-therapy) of times. Also, nucleus was different 52%
of times between conditions (pre-, and post-therapy).
Eighth, various types of nuclear tones that occurred included low rising (LR), low
falling (LF), low rising-falling (LRF), low falling-rising (LFR), level (1), risingfalling-rising (RPR), high-rising (HR), high-falling (HP), high rising-falling (HRF)
and high falling-rising (HFR). Compared to post-therapy condition HP nuclear tone
was significantly higher and RFR nuclear tone was significantly lower in pre-therapy
conditions in the groups that underwent prolonged speech technique and modified
airflow therapy, respectively. In the group, which underwent prolonged speech
technique LFR nuclear tone in pre-therapy, and LR, LFR and RFR in post-therapy
were significantly higher compared to normal subjects.
In the group, which
underwent modified airflow therapy LFR nuclear tone was significantly higher in
both pre- and post-therapy condition, compared to normal subjects. LFR nuclear tone
in pre-therapy and LFR, RFR and HFR nuclear tones in post-therapy were
significantly higher compared to normal subjects.
Ninth, no significant difference between groups, and conditions was observed on
maximum FO. Also, no significant difference between PWS in pre- and post-therapy
condition and normal subjects was noticed. However, the maximum PO in posttherapy condition was lower in PWS who underwent modified airflow therapy and
higher in the PWS who underwent prolonged speech technique compared to normal
subjects. Table 48 shows mean and SD values of maximum FO across conditions.
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Conditions/therapy
technique
Prolonged speech
technique
Modified airflow
therapy
Total
Normal subjects
Post-therapy
Pre-therapy
Mean
SD
Mean SD
Mean SD
154.79 17.58 154.40 27.50
154.01 22.17
142.98 19.04 141.01 17.71
148.63 18.93 147.41 23.40
Table 48: Mean and SD values of maximum FO (Hz) across conditions and therapy
techniques.
Tenth, no significant difference between groups of PWS, and conditions on FO range
was found. Post-therapy FO range was higher in PWS who underwent prolonged
speech technique and lower in PWS who underwent modified airflow therapy
compared to normal subjects, though not significantly. Table 49 shows mean and SD
values of FO range across conditions and therapy techniques.
Conditions/therapy
technique
Prolonged speech
technique
Modified airflow therapy
Total
Pre-therapy Post-therapy
Mean SD Mean SD
28.88 9.81 32.55 16.08
Normal
subjects
Mean
SD
29.54
7.53
24.48 4.44 24.40 3.65
26.58 7.66 28.30 11.90
Table 49: Mean and SD values of FO (Hz) range across conditions.
Eleventh, various types of errors in intonation were observed in the reading sample of
PWS. These included reduced length of intonation group, reduced frequency range
and increased number of stressed syllables in head.
In summary, results of the present study indicated that the percent dysfluency and
SPM significantly reduced in post-therapy condition compared to pre-therapy
condition. Also, SPM was significantly lesser in post-therapy condition compared to
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normal subjects. MNS was significantly less natural in PWS compared to normal
subjects.
Disfluency analysis revealed an increase in non-discrepant type of intonation in the
fluent pre-therapy and post-therapy condition compared to dysfluent pre-therapy
condition. PWS had more of shorter intonation group length (0-5 syllables) in preand post-therapy conditions compared to normal subjects. Nuclear syllables were
different, at least in some instances, in PWS. Nuclear tones used by stuttering group
and normal subjects differed to some extent. Various intonation errors such as
reduced length of intonation group, increased number of stressed syllables, incorrect
intonation groups, occurrence of rising nuclear tones in intonation group final
position, and reduced FO range were observed in PWS.
Based on the results all three hypotheses - Hi hypothesized that there would be no
significant difference between the intonations of pre- and post therapy speech samples
in PWS. H2 hypothesized that there would be no significant difference between the
intonation of pre-therapy speech of PWS and normal controls. H3 hypothesized that
there would be no significant difference between the intonation of post-therapy
speech of PWS and normal subjects - were rejected.
Although, the results throw light on the intonation of stutterer's speech, there iexist a
lot of subject variability. It may be impossible to rule out subject variability in PWS.
Also, the intonation analyses were done prior to and after the therapy. Thus, one does
not know the time at which a correct intonation (tone group placement, length of
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intonation group, among others) is mastered. Following the patient in each session is
warranted to obtain such information.
The material used was a reading passage. The reading passage was a story, which
consisted of dialogues. Thus it may be considered equivalent to conversation.
Therefore, the length of tone groups and placement of nucleus may differ from one to
another depending on the importance of message s/he perceives. However, a recorded
story would provide the subject with a model on the type of intonation group and
placement of nucleus. Such effort in future studies will provide more information
about the abnormality of intonation used by PWS.
The results indicate that intonation needs to be corrected in PWS. At the end of
therapy, they need to be trained on use of appropriate intonation. Or, instead of
prolonged speech technique and modified air flow therapy that has been used in this
study, intonation therapies and their efficacy could be investigated.
Lund school provides a model for intonation. According to the model, intonation of a
sentence can be generated at various levels starting from the superficial sentence to
deep structure such as words or even contexts. This might probably be a good model
to test with. Intonation used by normal can be extracted and the algorithm for each
sentence can be generated and stored on to the computer memory. The intonation
pattern of PWS on the same sentence can be compared to normal pattem and verified.
This probably may provide information on the abnormality in PWS and whether the
intonation is fitting in to the tonal grid. It is a long way to go and research in this
direction is warranted.
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Languages and dialects differ in terms of stress, rhythm and intonation. India, a
multilingual country, provides enormous opportunities for research in this area. In the
present study the Mysoru-Bangaluru dialect has been used, as this is the one used
maximally in theatre/ cinema. Hence, further studies may be directed on other dialects
of Kannada, and languages other than Kannada to arrive at a clear pattern of
intonation used by PWS in that dialect or language.
Lastly, the present study has confirmed the results of the earlier studies on perceptual
measures of treatment efficacy and has contributed additional information in the area
of intonation and intonation errors in persons with stuttering. It is a tedious process to
investigate these errors in persons with stuttering and design specific therapy
technique. However, it is worth making an effort in this regard and future research on
this subject is warranted.
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