J. COMMUN. DISORD. 24 (1991). 237-249

CONTINUOUS DISCOURSE TRACKING: AN ANALYSIS OF THE PROCEDURE JANET REATH Center for Research

SCHOEPFLIN in Speech

and Hearing

and HARRY Sciences.

LEVITT

C&v University of New York

The method of continuous discourse tracking was evaluated in terms of the strategies by the talker and the types of responses elicited from the listener. Talker utterances classified into four categories: I. 2. 3. 4.

Complete repetition (of the initial utterance); Partial repetition; Repetition with change in emphasis; and A combined strategy using two or more correction

Listener

responses

were classified

used were

strategies.

into three categories:

I. Correct repetition of intended utterance: 2. Partially correct repetition; and 3. Totally incorrect repetition or no response. The listeners showed small but statistically significant differences in their response patterns. Much larger differences were observed in the pattern of correction strategies used by the talkers. Differences in correction strategy were also observed between the early and later stages of a talker-listener exchange.

INTRODUCTION Current technology provides the hearing-impaired population with several types of sensory prostheses to assist in the reception of speech; these include hearing aids, vibrotactile and electrotactile devices, visual aids, and cochlear implants. Many of these devices have been demonstrated to be of benefit using traditional syllable, word, and sentence test materials. While these materials enable us to derive a standardized measure of speech recognition ability in the hearing-impaired population, their structure is not representative of everyday speech communication; i.e., we do not communicate by means of phonetically balanced lists of words or sentences. Address correspondence to Harry Levitt. Sciences, Graduate School, City University NY 10036.

0

1991 by Elsevier

655 Avenue

Science

of the Americas,

Publishing New

Co..

York.

NY

Inc. 10010

Center for Research in Speech and Hearing of New York, 33 West 42nd St., New York.

237 002 l-9924/91/$3,50

238

J. R. SCHOEPFLIN

and H. LEVITT

An important characteristic of human communication is the interaction between talker and listener, particularly when the listener does not hear everything that is said. A technique that attempts to take talker-listener interactions into account is that of continuous discourse tracking (De Filippo and Scott, 1978). Briefly, the procedure requires that the listener repeat verbatim segments of text spoken to him/her by the talker. If the listener makes an error, the talker selects one (or more) of several verbal repair strategies to achieve accurate message repetition by the listener. Test sessions are timed and the rate at which the listener is able to track the talker correctly, in words per minute, is used as a measure of speech reception ability. Because of its simplicity, ease of administration, and high face validity, the method of continuous discourse tracking has found widespread application in the evaluation of sensory prostheses, particularly in the evaluation of cochlear implants and tactile aids. Currently. however, the procedure is unstandardized and subject to a number of methodological variables. Improper control of these methodological variables can result in a substantial and unnecessary increase in test-retest variability. Variability arises from three primary sources-differences among test materials, such as level of difficulty, talker differences, and procedural differences. Differences among test materials are the result of the familiarity, linguistic complexity, and contextual predictability of the text being used, and may account for wide disparities in tracking rates between the same talker-listener pairs (Cholewiak and Sherrick, 1986: Reath. 1984; Hochberg et al., 1989). Clearly. the use of a standardized text would significantly control this factor. Talker differences are reflected in the delivery of the text to the listener, and include such features as voice quality, articulation, accent, and lip and facial postures, all of which may vary intrapersonally as well as interpersonally. It is possible to reduce this source of variability by using prerecorded test materials. In order to maintain the essential nature of continuous discourse tracking, however, an interactive method of selecting appropriate recordings based on the listener’s responses needs to be developed. This could be done using prerecorded utterances under computer control (Pickett, 1983; Levitt, 1988). In order to do so, however, it is first necessary to document typical patterns of interaction (between talker and listener) so that the rules for programming such a system can be developed. Procedural differences are closely linked to talker differences since it is the talker who maintains control over the procedures that will be followed in a given tracking session. While continuous discourse tracking is an interactive process involving both talker and listener, it is the talker who chooses the length of utterance to be tracked, judges the acceptability

CONTINUOUSDISCOURSETRACKING

239

of the listener’s responses, selects the type and sequence of strategies to use following an error by the listener, and sets any arbitrary limits on time or on the number of strategies to be used in a particular error situation. Talkers vary in how they manage a tracking session and this source of variability has a significant effect on the tracking rates achieved by their listeners. The purpose of this study was to investigate talker-listener interactions in continuous discourse tracking. The immediate objective was to quantify these interactions in a systematic way. The long-term objective is to develop practical rules for reducing variability caused by procedural differences. A second long-term objective is to use this information to develop a computerized version of continuous discourse tracking in which prerecorded utterances are used to reduce or eliminate the problems associated with intertalker differences.

METHOD Recordings of typical tracking sessions were obtained from three sources, an ongoing study involving the rehabilitation of cochlear implant patients, an ongoing evaluation of a tactile sensory aid, and tracking by a normal listener using noise to mask the speech signal. These samples were then transcribed in order to codify the strategies used by the talkers and the types of responses obtained from the listeners. Eight recordings of continuous discourse tracking were analyzed. In these tracking sessions, which lasted roughly 20 minutes each, three adult talkers were paired with five adult listeners. All three talkers were normalhearing speakers of standard American English. Three of the listeners were profoundly hearing-impaired individuals and the other two were normally hearing individuals temporarily deafened with insert ear plugs and masking noise. Each of the tracking sessions was transcribed. Of particular interest in these transcriptions were the repair strategies used by each talker in correcting the listener and the types of responses produced by each listener. All of the talkers were experienced in the method of continuous discourse tracking and followed the procedures recommended by De Filippo and Scott (1978) as closely as they could. The correction strategies employed by the talkers were found to be similar to those reported by Erber and Greer (1973) for teacher-child exchanges at a school for hearing-impaired children. This was expected since the method of continuous discourse tracking was modeled on exchanges of this type. As a consequence, a classification scheme similar to that used by Erber and Greer (1973) was used in codifying the talkerlistener interactions. The strategies used by the talkers in correcting the listener’s repetitions were subdivided into four categories:

240

and H. LEVITT

J. R. SCHOEPFLIN

I. Complete repetition, in which the entire target utterance is repeated without modification; 2. Partial repetition, in which a portion of the target utterance is repeated without modification; 3. Change in emphasis, in which all or part of the target utterance is repeated with significant modifications in stress pattern and articulatory effort; and 4. Combination of strategies, in which the talker uses a combination of strategies including the use of different words or phrases having essentially the same meaning. The listener’s

repetitions

were classified

into three categories:

1. Correct repetition of talker’s utterance; 2. Partially correct repetition of talker’s utterance; 3. Totally incorrect repetition or no response.

and

A count was made of each type of correction strategy used by the talker and of each type of response produced by the listener. These were collated in terms of a flow diagram showing the pattern of talker-listener interactions.

RESULTS A total of 1025 talker utterances and a corresponding number of listener responses were observed in the eight tracking sessions. Of the talker utterances, 412 (40.2%) were initial utterances, i.e., utterances used by the talker in initiating a new sequence of talker-listener exchanges. Typically, a sequence of exchanges is terminated when the listener repeats the target utterance correctly. A new sequence is then initiated with the talker producing a new initial utterance. The remaining 613 talker utterances (59.8%) were correction utterances in which some form of repair strategy was used by the talker. A flow diagram detailing the sequence of events is shown in Figure 1. The talker begins each sequence with an initial utterance (Tl). The listener responds with either a correct (Llc) or incorrect (Lie) repetition of the utterance. These two events constitute a trial. The nature of the listener’s response determines the next trial. If the listener repeats the initial utterance correctly (Llc), the sequence is terminated and a new sequence is initiated by the talker. If the listener responds incorrectly (Lle) the sequence continues into, the next trial, which begins with a correction utterance produced by the talker (T2). This is followed by the listener’s response which, if correct (L~c), terminates the sequence. If the listener’s repetition is incorrect (L2e), the sequence continues with a third trial. The procedure continues iteratively until the listener has finally re-

241

CONTINUOUS DISCOURSE TRACKING LlSTENER

TALKER

TRLKEH

Trial l

,Corrcct 1

Initial

Utterance

[ >I”corrcct

2

” Correction

I

Aaprtation

(Llc)+Nrvt

Initial uttrrancc

(Tl)-

Utterance

(T2)-

Utterance

(T3)-

Repetition

(Llc)

v 3

Correction

l

l-----------

& 17

Correction

)Corrcct Utterance

Repetition

(Lnc)->Ncxt

tTn)-

[> Incorrect

Rep& it ion

Initial Ut t l -mcr

(Lnc)

Figure 1. Flow diagram of talker-listener sequence. The sequence begins with an initial utterance on Trial 1. If the listener repeats the utterance correctly, the sequence is terminated. If the listener’s response is incorrect (either partially or totally) the next trial is initiated with a correction utterance of some kind. The procedure continues iteratively until the listener has repeated the initial target utterance correctly.

peated the target utterance correctly. All of the talker utterances and listener responses were classified according to the categories described above (i.e., four categories of talker utterances and three categories of listener responses). The total number and relative frequency of talker utterances and the corresponding listener responses are shown as a function of trial number in Table 1. The data show that the percent of correct repetitions on each

242

J. R. SCHOEPFLIN

Table 1. Frequency

Function

of Talker Utterances of Trial Number Talker

Trial number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Number of utterances 412 232 145 87 52 28 17 15 11 7 6 4 2 2 2 2 1

Percent of total number of utterances

Number of correct repetitions

40.2 22.6 14.1 8.5 5.1 2.7 1.7 1.5 1.1 0.7 0.6 0.4 0.2 0.2 0.2 0.2 0.1

180 87 58 35 24 11 2 4 4 1 2 2 0 0 0 1 1

” Indicates estimate of low accuracy because ’ Indicates

too few utterances

and Correct Listener Repetitions Correct

utterances

for a meaningful

and H. LEVITT

listener

repetitions

Percent correct on current trial

Percent of total number of repetitions

43.1 31.5 40.0 40.2 46.2 39“ 12” 27” 36” 14” 33“ 50” b h h h h

43.7 21.1 14.1 8.5 5.8 2.7 0.5 1.0 1.0 0.2 0.5 0.5 0 0 0 0.2 0.2

of small number estimate.

as a

Comulative percent correct 43.1 64.8 78.9 87.4 93.2 95.9 96.4 97.4 98.4 98.6 99.1 99.6 99.6 99.6 99.6 99.6 100.0

of utterances.

trial remains roughly constant (approximately 40%) until the fifth or sixth trial. The average percent correct repetitions for the first five trials was 41.4% (standard error = 1.6%). This average was obtained by weighting each percent correct score by the number of utterances repeated on each trial. The percent of correct responses per trial then falls well below 40% after the sixth trial. Note that since the number of talker utterances for the sixth and higher trials is relatively small, the precision with which a percent correct repetition can be estimated for each trial is relatively poor. A more precise estimate can be obtained by averaging the percent correct responses over a sequence of trials. The weighted average of percent correct repetitions for all trials beyond the sixth is 24.6% (standard error = 5.2%), which is significantly less than 41.4% (standard error = I .6%). It should also be noted that since the percentage of correct responses per trial is lower for the later trials, the number of talker utterances for subsequent trials is reduced correspondingly. As a consequence of these two effects (reduced percent correct repetitions and fewer talker utterances with increasing trial number), there is a sharp decrease in the rate at which the cumulative percentage of correct responses increases with

243

CONTINUOUSDISCOURSETRACKING Table 2.

Talker Talker

Utterances

and

Listener

Repetitions

Summed Listener

utterances

over

All

Trials”

repetitions

Frequency Type

of utterance

Complete Partial

repetition

repetition

Change

in emphasis

Combined

strategies

Row subtotals ” The numbers of talker talker

utterance.

of

Correct

Partially

Totally

utterance

repetition

correct

incorrect

36 [7.0%]

14 (39%)

9 (25%)

13 (36%)

338 [65.5%]

132 (39%)

131 (39%)

75 (22%)

123 [23.8%]

21 (17%)

50 (41%)

52 (42%)

19 [3.7%]

8 (42%)

5 (26%)

6 (32%)

516 [lOO%I

204 (39.5%)

197 (38.2%)

I I5 (22.3%)

in parentheses The

numbers

show

the frequency

in brackets

show

of listener

repetitions

as a percentage

the percent

frequency

of occurrence

for each type of each type

of

utterance.

trial number. For example, at the end of the second trial, 64.8% of the sequences have been terminated by a correct repetition. This percentage increases to 78.9% by the third trial and by the fifth trial it is 93.2%. Beyond the fifth trial, however, the cumulative percentage of correct responses increases very slowly and an additional 12 trtals are needed in order for every talker-listener exchange to end in a correct repetition. A more important difference between the early and late trials is that the talkers showed much greater variability in the choice of correction strategies for sequences involving more than five trials. Some talkers grossly exaggerated the articulatory and prosodic characteristics of the utterance, others attempted to spell out words with which the listener was having particular difficulty, while others employed visual gestures which, strictly speaking, should not be used in continuous discourse tracking. In view of the above problems, particularly the large, individual differences in repair strategies for the long talker-listener exchanges, it was decided to focus the analysis on the first five trials. Since the number of sequences exceeding five trials was small (less than 7% of the total number), it is unlikely that statistically reliable information on the pattern of talker-listener interactions could be obtained from an analysis of the very long talker-listener exchanges. Table 2 shows the frequency of occurrence of the four types of correction utterances used by the talker and the different types of listener responses. The first entry in each cell of the data matrix shows the total count for each utterance type, summed over Trials 2-5. Data for Trial I are not included in the table since there were no correction utterances on this trial. The numbers in parentheses show the percent frequency of occurrence of each response type for each type of talker utterance, i.e., these percentages sum to 100% for each row. The numbers in square

244

J. R. SCHOEPFLIN

and H. LEVITT

brackets (column 2) show the percent frequency of occurrence of each type of talker utterance; i.e., these percentages sum to 100% for this particular column. The contingency table shown in Table 2 was subjected to a chi-square analysis. No significant interaction between listener repetitions and utterance type was observed (chi-square = 8.3, 6 degrees of freedom). Correct and partially correct listener repetitions occurred roughly equally often on the average (just under 40% of the time for each type of response). Totally incorrect listener repetitions (or no response) occurred much less frequently, about 20% of the time. This pattern of listener responses was much the same for each type of correction utterance used by the talker. The frequency of occurrence of the different types of correction utterance differed significantly, the most common repair strategy being a partial repetition of the target utterance (65.5%). A change in emphasis was used much less often (23.8%) and a combined strategy was seldom used (3.7%) during the first five trials. Complete repetitions were used fairly infrequently (7.0%, on the average). Table 3 shows the frequency of listener repetitions for each type of talker utterance for each of the five trials. Note that there is only one type of talker utterance in the first trial (the initial utterance). A chi-square analysis showed a significant interaction between type of talker utterance and trial number (chi-square = 49.5, 9 degrees of freedom, p < .OOl); i.e., the data show a change in repair strategy (type of talker utterance) within a sequence of trials. The use of complete repetitions dropped sharply from 13% on Trial 2 to 3% or lower on Trials 3, 4, and 5. The use of partial repetitions increased slightly in going from the second to the third trial. Change in emphasis was used at a fairly constant rate (about 25% of the time) until Trial 5 when its usage dropped significantly. Combined correction strategies were hardly used during the first two trials, after which there was a rapid increase in the use of this repair strategy. A second significant interaction was observed between listener response and trial number for partial repetitions by the talker (chi-square = 18.1, 6 degrees of freedom, p < .Ol). The data show a relatively low frequency of correct listener repetitions on Trial 2 (29% vs. 50% for partially correct repetitions), whereas on the remaining trials, the listener was more likely to respond with a correct rather than partially correct repetition (e.g., 44% vs. 36% on Trial 3, 44% vs. 26% on Trial 4, and 54% vs. 23% on Trial 5). The data were also analyzed to determine if there were any differences in either the talker or listener strategies for different talker-listener combinations. Small differences were observed among talker-listener pairs in terms of the relative frequency of different response types. Table 4 shows a comparison between two talker-listener pairs in which significant differepces in listener response patterns were observed. The data show

CONTINUOUS

DISCOURSE

Table 3. Listener Number” Talker

TRACKING

Repetitions

for

Each

245

Type as a Function

Utterance

utterances

Listener

of Trial

repetitions

Frequency of utterance

Trial

Initial utterance

412 [lOO%]

I

Complete repetition Partial repetition Change in emphasis Combined strategies Row subtotals

30 140 60 2 232

]13%] [60%] [26%] [I%] [lOO%]

2

I3 41 32 I 87

Complete repetition Partial repetition Change in emphasis Combined strategies Row subtotals

4 102 36 3 145

[3%] [70%] [25%] [2%] [lOO%]

3

Complete repetition Partial repetition Change in emphasis Combined strategies Row subtotals

4

57 21 8 87

Complete repetition Partial repetition Change in emphasis Combined strategies Row subtotals

39 6 6 52

Type of utterance

1 [l%]

talker

utterance.

The

numbers

5

the frequency

in brackets

show

2 2 2 3 3 3

Totally incorrect

I53 (37%)

79 (19%)

(43%) (29%) (53%) (50%) (38%)

8 70 21 I 100

(27%) (50%) (35%) (50%) (43%)

9 29 7 0 45

I 45 IO 2 58

(25%) (44%) (28%) (67%) (40%)

I 37 I7 0 55

(25%) (36%) (47%) (0%) (38%)

2 (50%) 20 (20%) 9 (25%) I (33%) 32 (22%)

0 25 7 3 35

(44%) (33%) (38%) (40%)

0 I5 II 3 29

(26%) (52%) (38%) (33%)

I I7 3 2 23

(30%) (14%) (25%) (27%)

0 9 (23%) 3 (50%) l(l7%) 13 (25%)

I 9 2 3 15

(23%) (33%) (50%) (29%)

0 21 (54%) I(l7%) 2 (33%) 24 (46%) of listener

repetitions

the percent

frequency

as a percentage of occurrence

(30%) (21%) (12%) (0%) (19%)

for each type of each type

of

utterance.

Table 4. Listener Response Following Data Are Shown for Two Replications Talker-Listener Pairs Talker

correct

IS0 (44%)

[75%] [IIS%] [ll.S%] [lOO%]

show

Partially

repetition

[66%] [24%] ]9%] ]lOO%]

I [2%]

” The numbers in parentheses of talker

Correct

tl0.

Listener 3 3 3 4 4 4

Replication I 2 li2 I 2 I+2

Partial Repetition by Talker, Trial 2. of the Tracking Task for Each of Two Correct repetition

Partially correct

Totally incorrect

7 I7 24 5 5 IO

II I6 27 II 17 28

3 ( 14%) 2t 5%) 5( 9%) II (41%) 6 (21%) I7 (31%)

(33%) (49%) (43%) (18%) (18%) (18%)

(53%) (46%) (48%) (41%) (61%) (51%)

246 Table 5.

J. R. SCHOEPFLIN Correction

Strategies

Used by Three Talker-Listener Correction

Talker

Listener

2

3

3

4

3

5

2

3

3 3

and H.

LEVITT

Pairs

utterances

Trial

Complete

Partial

Change in

Combined

No.

repetition

repetition

emphasis

strategies

2

24 (23%) 2(

3%)

5%)

56 (54%)

24 (23%)

O(

41 (70%)

14 (24%)

2 2(

4%) 2%)

(

3%)

O(

0%)

26 (52%)

22 (44%)

2(

3%)

46 (79%)

9 (16%)

4

I(

2%)

13 (24%)

5

O(

0%)

39 (72%) 16 (57%)

I( I(

12 (43%)

O(

0%) 3%)

3

2%)

2

3

O(

0%)

22 (69%)

9 (28%)

I(

3

4

I(

3%)

24 (64%)

8 (22%)

4 (11%)

3

5

O(

0%)

1I

4 (23%)

2 (12%)

4

(65%)

2

3

O(

0%)

13 (86%)

I(

3

4

I(

4%)

3 (12%)

3 (12%)

3

5

O( 0%)

19 (73%) 7 (70%)

2 (20%)

I (10%)

5

7%)

I(

7%)

frequency of listener repetitions after a partial repetition by the talker on Trial 2. Two replications of the tracking task were analyzed for each of two talker-listener pairs. No significant differences in the pattern of listener repetitions were observed between replications within a talker-listener pair, but a statistically significant interaction between different talker-listener pairs was observed (chi-square = 12.3, 2 degrees of freedom, p < .005). Listener 4 with Talker 3 showed a higher frequency of totally incorrect responses and a lower frequency of correct repetitions than Listener 3 with Talker 2. Interactions of this type reflect different levels of performance by the listener and are not necessarily related to the repair strategy used by the talker. Table 5 shows how different repair strategies were used by different listener pairs. The pattern of correction utterances is shown for three talker-listener pairs, Talker 2 with Listener 3, Talker 3 with Listener 4, and Talker 3 again with a different listener (Listener 5). Data for these three talker-listener pairs (2, 3), (3,4), and (3, 5), respectively, are shown for Trials 2-5. A chi-square analysis of the contingency tables show significant differences on Trial 2 in the pattern of correction utterances used by the two talkers. Talker 2 made much heavier use of complete repetitions in comparison with Talker 3. There was also a small, but statistically significant interaction between the two talker-listener pairs involving Talker 3. For Listener 5, Talker 3 made much greater use of change in emphasis as a correction strategy, whereas for Listener 4, much greater use was made of partial repetitions. These differences in correction strategy are

CONTINUOUS

DISCOURSE

TRACKING

247

less evident in subsequent trials. This may be because there are fewer data for making reliable comparisons as trial number increases. Data were also obtained on average utterance length. The average number of words in an initial utterance ranged from 3.4 to 5.5 for the five talker-listener pairs. Relatively long utterances of 8 words or more were used infrequently (about 5% of the time), while very short utterances of 1 or 2 words were used about 20% of the time. Correction utterances were usually much shorter than initial utterances; in particular, partial repetitions of only one or two words were often used.

DISCUSSION The data show that the most common repair strategy is that of a partial repetition. The average frequency of partial repetitions by the talker was 65.5%. The use of partial repetitions was slightly less frequent on the first use of a repair strategy (Trial 2). Greater use was made of complete repetitions on this trial (13%) than on any other. Complete repetitions were hardly used on the third and subsequent trials. A complete repetition can be a relatively efficient repair strategy when the listener responds correctly. If the listener responds incorrectly this repair strategy is relatively inefficient. All of the talkers, who were experienced in the tracking task, appear to have judged well in terms of when to use a complete repetition. Complete replications were only used during the very early trials in a talker-listener exchange. At this stage in the sequence, there was a reasonable expectation that the listener might still be able to repeat the entire initial utterance correctly. The frequency of correct listener repetitions to either an initial utterance or a complete talker repetition was relatively high at the start of a sequence (44% on Trial I, 43% on Trial 2). In contrast, the frequency of correct listener responses to a partial repetition was comparatively low the first time this repair strategy was used (29% on Trial 2), but increased significantly to well over 40% on subsequent trials. The use of a change in emphasis as a repair strategy did not vary in frequency by very much across trials. It was used about a quarter of the time and, on the average, was the second most widely used repair strategy. The relatively low frequency of occurrence observed for change in emphasis (I 1.5%) on Trial 5 may have been a result of the increasing use of combined correction strategies as the number of incorrect listener repetitions increased. The combined strategies method of correction appears to have been used as a means of last resort. It was hardly used during the early trials in a sequence, but its use increased on later trials. This was especially for sequences in excess of five trials, as it became evident that the two

248

J. R. SCHOEPFLIN

and H. LEVITT

most common repair strategies (partial repetition and change in emphasis) were not working. Statistical analysis of the data showed some significant differences in the pattern of listener responses, but these were small in comparison with the more highly significant differences in the correction strategies used by the talkers. Correction strategies varied not only as a function of trial number, but also between talkers and, to a lesser extent, with the same talker when paired with a different listener. The largest differences were observed during the early stages of a talker-listener sequence. Large differences were also observed, informally, for very long sequences but these could not be tested reliably because of the small sample size (fewer than 7% of the talker-listener sequences extended beyond five trials). Several major difficulties were encountered with tracking sequences involving more than five trials. These included the use of idiosyncratic repair strategies, occasional use of visual or other nonaural cues and, with very long sequences, a substantial increase in test-retest variability; e.g., tracking rate can be decreased substantially (and in a nonrepresentative way) if a single very long sequence occurs in a tracking experiment. Whereas the large majority of talker-listener exchanges involved fewer than five trials, some sequences were over three times as long. Because of the many difficulties associated with very long trials, it is recommended that tracking sequences be terminated after the fifth trial. At this stage, the utterance could be shown to the listener as text on a screen and the next talker-listener sequence initiated. This step would greatly increase the precision and reliability of the tracking procedure. The fifth trial represents a convenient stage at which to terminate a talkerlistener sequence, since as shown in Table I, the rate at which talkerlistener sequences are terminated falls off rapidly after the fifth trial; i.e., once the fifth trial is reached it is likely that the talker-listener sequence will continue for many more trials unless the sequence is truncated without a final correct response from the listener.

CONCLUSIONS The data obtained in this study provide a concise summary of the pattern of talker-listener interactions in continuous discourse tracking for three talkers experienced in the implementation of this procedure. Although the number of talkers is too small to generalize to the population of all talkers using this technique, it is significant to note that the three talkers come from three separate laboratories using this technique independently. Although there were significant intertalker differences, the general response patterns and subsequent repair strategies were similar in many respects. Sequences of more than five trials showed a number of problems, not

CONTINUOUS

DISCOURSE

TRACKING

249

least of which was the informal observation of substantial differences in repair strategy for very long talker-listener sequences. Given this problem, the relative low gain in information with increasing sequence size and the resulting increase in test-retest variability, it is recommended that tracking sequences be terminated after the fifth trial. The

research

National

reported

Institute

in this paper

on Disability

Waltzman

of New

University

for providing

York

was supported

and Rehabilitation

University

Medical

Center

us with video recordings

by grant

Research. and Dr.

No.

H133E80019

We are grateful Carl

Sherrick

of tracking experiments

from

the

to Dr. Susan of Princeton

performed

in their

laboratories.

REFERENCES Cholewiak, long-term 26. DeFilippo, reception

R. W., and Sherrick, tactile aid experience:

D. (1986). Tracking skill of a deaf person with A case study. J. Rehab. Res. Dev. 23(2):20-

C., and Scott, B. (1978). A method for training and evaluating of ongoing speech. J. Acousf. Sm. Am. 63: 1186-l 192.

Erber, N., and Greer, C. (1973). Communication strategies an oral school for the deaf. Volta Rev. 79135-42. Hochberg, I., Rosen, connected discourse Levitt,

Reath,

used by teachers

S., and Ball, V. (1989). Effect of text complexity tracking rate. Ear Hear. IO: 192-199.

H. (1988). Videophonetics.

Pickett, J. (1983). Theoretical electroauditory stimulation. J. (1984). Unpublished

J. Acoust.

Sot.

Am. 84(Suppl.

at

upon

I):S46-S47.

considerations in testing speech perception Ann. N. Y. Acad. Sci. 4:424-434. study.

the

through

Continuous discourse tracking: an analysis of the procedure.

The method of continuous discourse tracking was evaluated in terms of the strategies used by the talker and the types of responses elicited from the l...
793KB Sizes 0 Downloads 0 Views