Journal o f Psycholinguisffc Research, Vol. 1, No. 2, 1972

Pause Time and Phonation Time in Stuttering and Cluttering R. W.

Rieber,x Stephen Breskin, 2 and Joseph Jaffe 2

Received September 1, 1971

This study examined the potential usefulness o f automated analysis o f on-off speech patterns in the differentiation o f stuttering from cluttering. Two groups o f fifteen persons who had been previously classified as stutterers and clutterers served as sub/ects for this investigation. The data indicate that stutterers tend to have greater mean pause times and lower mean phonation times than clutterers. This result corresponds to the clinically observable characteristics o f these groups. It is ,concluded that automated analysis of on-off speech patterns provides some basis for the differential diagnosis o f stuttering from cluttering.

INTRODUCTION Both stuttering and cluttering are communicative disorders classified as disturbances of rhythm and rate. Stuttering is defined in this investigation as a class of fluency failure characterized by blockings, repetitions, and prolongations in the rhythmic flow of speech. In contrast, cluttering is defined as a class of fluency failure characterized by a rapid rate of utterance accompanied by repetitions, additions, inversions, omissions, and distortions of sounds, syllables, words, or phrases. Supported, in part, by a general research support grant from NIMH to the Research Foundation for Mental Hygiene, Inc. 1Pace College, New York, New York, and John Jay College, City University of New York, New York, New York. 2Department of Communication Sciences, N.Y. State Psychiatric Institute, New York, New York. 149

1972 Plenum Publishing Corporation, 227 West 17th Street, New York, N.Y. 10011.

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Rieber, Breskin, and Jaffe

Stutterers and clutterers have been comparatively studied, using techniques such as the electroencephalograph, delayed side tone, administration of drugs (Langova and Moravek, 1966), and the sophistication of body concept (Rieber, 1963). A hypothetical relationship between stuttering and cluttering has also been proposed (Weiss, 1966; West, 1957; Bloodstein, 1958). For example, Weiss developed a theory which suggests that stuttering has its origin in the problem of cluttering. There is little experimental data, however, to help understand how these two problems may be related. Johnson (1961) points out that the measurement of the oral rate of stuttering and cluttering is of fundamental importance, especially in terms of differential diagnosis. In the present study we focus our attention on two independent components of oral reading rate (i.e., mean pause time and mean phonation time). These parameters have not heretofore been studied in the differential diagnosis of stuttering and cluttering. Specifically, the purpose of this research is to investigate whether pause time and phonation time differ significantly between stutterers and clutterers.

PROCEDURE

Thirty persons who had been previously classified as stutterers and clutterers respectively served as subjects for this investigation. The subjects were classified by the experimenter and two independent judges. Each judge was given a sheet of instructions containing the criteria used in defining cluttering and stuttering as stated in the first paragraph of this paper. The judges then listened to the tape-recorded speech samples. Each subject was then classified by the judges as predominantly a stutterer or predominantly a clutterer. Along with this diagnostic classification, each judge rated all the subjects in terms of the severity of their stuttering or cluttering, respectively. A three.point rating scale of mild, moderate, and severe was utilized. No specific criteria were given to the judges for their severity ratings. Fifteen subjects were classified as stutterers, and fifteen were classified as clutterers. These subjects were then equally distributed in terms of age, sex, and severity. All of the subjects in this study were males. Their ages ranged from 17 to 28 years. Each subject was naive as to the purpose of the experiment. The subjects read a standard controlled passage six successive times, a The same reading passage was used for all the subjects in the study. After the subject was seated, the following instructions were given: 3There was a 7-rain rest period between readings five and six.

Pause Time and Phonation Time in Stuttering and Cluttering

151

Turn over the page which will be placed face down before you. Read it aloud in your normal conversational manner. Except for the oral reading you are not to speak at any time while the experiment is in progress. Ate there any questions? Twenty inches to the right of the subject was a plug-type microphone which was connected to a tape recorder situated under the table. In front of the experimenter was a stopwatch and a folder containing the instructions and reading passages. After the subject was seated, he was instructed to begin oral reading. The experimenter at this point activated the tape recorder. The oral readings and tape recordings took place during trials one to six. During the oral reading the experimenter followed along with a copy of the passage. At the completion of each oral reading the experimenter took the reading passage from the subject. Just before the start of the next trial the experimenter placed another copy of the passage face down before the subject.

ANALYSIS OF SPEECH DATA

The time taken to read the standard passage varied between I and 2 rain, with each subject and with each replicated reading. Consequently, in order to maintain an equivalent performance from all subjects, only the first minute of each subject's reading sample was considered for the subsequent speech analysis. Jaffe and Feldstein (1971) sampled, in 300-msec intervals, the presence or absence of vocalization on the tape-recorded speech samples. In order to use this device in our study, certain instrumental adjustments were required. The threshold setting determines the level above or below which the converter decided the presence or absence, respectively, of the speech signal. After listening to the tapes, an optimal threshold level, which included speech but excluded background noise, was selected and standardly used for the processing of all tapes. The gain setting of the converter permits the user to raise or reduce the intensity of the speech sample being processed. The gain was set such that the subjects' intensity varied between -20 VU and 0 VU. With reference to the preset threshold, the absence of speech is designated state 0 and the presence of speech state 1. (Observations of adjacent samples

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in the identical state are presumed to have been continuous in the interval between samples.) In order to make the output of the converter comparable to what the human ear perceives, a tail ("hangover time") of 150 msec was added to each vocalization in order to bridge minimal pauses referable to stop consonants. Once the above parameters were set, the instrument was able to generate strings of O's (silence) and 1 's (sound). At the conversion rate of 5 per second, each l-rain speech recording was replaced by a string of 300 zeroes and ones. An on.line PDP-8/I computer generated two frequency distributions; one for the O's and one for the l's. The mean of each distribution is concurrently obtained by the computer, and these means represent the dependent variables. The mean pause time and mean phonation time, for each subject and for each of the six replicated readings, are the raw data for the s~bsequent statistical analysis. 4 A two-factor analysis of variance was used to analyze the results (Winer, 1962). The analysis of variance was performed separately on the pause and phonation times. Raw scores were transformed to achieve normality (see Breskin and Jaffe, 1970). Table I shows the results for mean pause times and Table II shows the results for mean phonation time. The results for the stuttererclutterer distinction, summed over trials, is shown in Table III. In addition, Table ]II also shows the average mean pause and mean phonation times for a group of 24 "normal" speaking male college students, performing an oral reading task for 5 rain (Bre~in, 1970). Table I shows a significant effect between stutterers and clutterers, and in conjunction with Table III, this indicates greaier mean pause times in 4Optimally, 180 min of tape are called by the experimental design. However, due to both noise on some of the tapes and availability of experimental subjects on others, 158 min of tape were processed.

Table I. Analysis of Variance on Mean Pause Time I

Source

I

df

Between subjects: (A) Subjects within groups Within subjects: (B) Trials

2_~.9 1 28 12_~8 5

A XB

5

B • subjects within groups i

ii

118 i

i

MS

F

P

0.622 0.035

17.771

0.01

0.004 0.014 0.016

1 1

ns ns

Pause Time and Phonation Time in Stuttering and Guttering

153

Table II. Analysis of Variance on Mean Phonation Time II

IPl

II

Source

df

Between subjects: (A) Clinical diag. Subjects within groups Within subjects: (B) Trials A• B B • subjects within groups I

I

II

I

MS

I

F

29 1 28

0.060 0.032

1.887

128 5 5 118

0.032 0.002 0.002

12.294 1.059

I

m

P ns

0.01 ns

I

i, ii

Table III. Mean Pause and Mean Phonation Times (in seconds) Mean pause time

Mean phonation time

Stutterer

Mean S.D.

0.432 0.132

1.290 0.531

Clutterer

Mean S.D.

0.333 0.069

2.05 3 1.675

"Normals" (24 males)

Mean S.D.

0.441 0.083

2.012 0.640

Ill

IH

Ill

II

III

II

IIII

stutterers than in clutterers. While Table II did not show a significant effect for stutterers and clutterers, it is apparent :from Table III that the stutterers tend to have shorter mean phonation times than either the clutterers or the norms group. On the other hand, the clutterers tend to have shorter mean pause times than either the stutterers or the "normals." It should be noted that the significant trials effect in Table II was unrelated to clinical diagnosis, and therefore not subject to the interest of this paper.

DISCUSSION We have examined the potential usefulness of automated analysis of on-off speech patterns in the differentiation of stuttering from cluttering. Table I indicated that the measure of mean pause time successfully distinguished the group of stutterers from clutterers, while Table II indicated that the measure of mean phonation time did not. This result is consistent

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Rieber, Bxesl~, and Saffe

with previous research, showing that pause measures are more sensitive to changes in experimental variables than are phonation measures (Jaffe and Feldstein, 1971; Cassotta, Feldstein, and Jaffe, 1967). Table III shows that stutterers tend to have greater mean pause times and lower mean phonation times than clutterers. This result corresponds to the clinically observable characteristics of these groups. In order to examine the nature of the difference between stutterers and clutterers, Table III presented additional results for a group of "normal" subjects. This table indicates that clutterers were similar on mean phonation time but deviated with shorter mean pause times while stutterers were similar on mean pause time but deviated with shorter phonation times. Caution should be exercised with this interpretation in that neither subjects nor stimulus materials were matched between norms and experimental groups. It is concluded from the above results that automated analysis of on-off speech patterns provides some diagnostic utility for the differentation of stutterers from clutterers.

REFERENCES Bloodstein, O. (1958). Stuttering as an anticipation struggle reaction. In Eisenson, J. (ed.), Stuttering: a Symposium Harper & Row, New York. Breskin, S. (1970). Individual differences in speech fluency under delayed auditory feedback. Unpublished doctoral dissertation, City University of New York. Breskin, S., and Jaffe, J. (1970). On the use of parametric statistical techniques to assess the on-off characteristics of speech, or. Psychol. 75, 41-44. Cassotta, L., Feldstein, S., and Jaffe, J. (1967). The stability and modifiability of individual vocal characteristics in stress and non-stress interviews, l~lliam Alanson White Instit. Res. Bull. No. 2. Jaffe, J., and Feldstein, S. (1971). Rhythms of Dialogue. Academic Press, New York. Langova, J., Moravek, M. (1966). An Experimental Study of Stuttering and Cluttering. Academia, Praha, Czechoslovakia. 9 Richer, R. W. (1963). A psychological investigation of the relationship between stuttering and cluttering. In Croatto, L. (ed.), Proceedings of the 12th International Speech and Voice Therapy Conference, I.A.L.P., Padua, Italy, pp. 371-376. Weiss, B. A. (1965). Cluttering. Prentice-Hall, Englewood Cliffs, N.J. West, R., Ausberty, M., and Ca~r, A. (1957). The Rehabilitation of Speech. 3rd ed. Harper & Row, New York. Winer, B. J. (1962). Statistical Principles in Experimental Design. McGraw-Hill, New York.

Pause time and phonation time in stuttering and cluttering.

This study examined the potential usefulness of automated analysis of on-off speech patterns in the differentiation of stuttering from cluttering. Two...
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