1 The Role of Pause Occurrence and Pause Duration in the Signaling of Narrative Structure Miguel Oliveira Instituto de Linguística Teórica e Computacional (ILTEC) Lisboa, , Portugal Abstract. This paper addresses the prosodic feature of pause and its distribution in spontaneous narrative in relation to the role it plays in signaling narrative structure. Pause duration and pause occurrence were taken as variables for the present analysis. The results indicate that both variables consistently mark narrative section boundaries, suggesting thus that pause is a very important structuring device in oral narratives. 1. Introduction Pauses are primarily considered to be periods of silence in the speech of a person (: 221). Obviously, not all periods of silence are pauses and not only periods of silence characterize a pause. In order for a period of silence to be considered a pause, it must occur between vocalizations. In other words, silent gaps that occur in speech as a result of taciturnity or reticence, for example, are not considered pauses. Additionally, other phenomena that do not necessarily correspond to the definition of pause presented above are sometimes considered to be so in the literature, such as filled pauses (vocal hesitations: "uh, "er, etc.), repeats, false starts, syllabic or vocalic prolongations, discourse markers, etc. (: 221). Pauses perform multiple functions. Their occurrence is determined by several factors such as anxiety, emphasis, interruption, intersubjectivity, availability, breathing, syntactic complexity, etc. (: 221). However, what necessitates pause is of little interest in this study. Rather, pauses are mainly regarded as a linguistic cue for narrative segmentation. It is generally accepted that among all the prosodic features available to the speaker for signaling structure in a text, pause is one of the most efficient (, , ). It is expected that at some points in the telling of a story, boundaries are more likely to occur than at other points. Such boundaries are often realized as a period of silence of varying length, in conjunction with other acoustic cues. In this paper it is hypothesized that the segmentation of narrative into sections is systematically evidenced in speech by means of pause occurrence and length speakers systematically signal the end of a narrative section by producing a pause of long duration. Pauses of shorter duration are, on the other hand, regarded as a cue for
2 non-finality speakers would use them to indicate that the following information has some sort of semantic connection with the previous one. 2. Methods The material used in the present study derives from a larger investigation on the role of prosodic features in the organization of spontaneous narratives (). A total of 17 narratives told in the course of a spontaneous interview () were chosen for this analysis. In order to avoid the so-called risk of circularity, a series of methodoligical procedures, which included the involvement of five experts in intonation and two experts in discourse analysis, were taken (see  for a detailed discussion on these procedures). A specific model of narrative analysis, the Labovian Evaluative Model (), was used for the purpose of the analysis. This study is restricted to silent pauses, defined by [13: 203] as a period of vocal inactivity of a certain duration embedded in the stream of speech. It does not include the occurrence of filled pauses or any other phenomena that include vocalization since they have a very limited incidence in speech (, ) and are not primarily used as a means of signaling boundaries in discourse (, ). There is very little agreement among researchers concerning the cut-off point for defining a silent pause. The range varies greatly, going from as long as 3 seconds () to as short as 80 milliseconds (). The most common cut-off point, however, is up to 250 ms after the precedent of Goldman-Eisler (, , , ). According to , the consequences of adopting a minimum cut-off point well above 250 ms are numerous, since 71.5% of all pauses occur in the duration interval between 250 ms and 1 sec (see also  for a similar claim). She also points out that the consequences of adopting no minimum cut-off point are serious as well, since short periods of silence which cannot be considered as psychologically functional pauses are required for articulation. Following the tradition initiated by Goldman-Eisler (, , , ), the present study adopts a cut-off point of 250 ms. for the definition of pause. 3. Pause occurrence as a narrative boundary predictor Table 1 below displays the number of absolute occurrences of pauses at narrative boundaries, at boundaries that do not correspond to narrative boundaries and of pauses found elsewhere in the narratives.
3 Table 1. Distribution of pauses: total number of occurrences (percentages in parenthesis) at narrative boundaries, non-narrative boundaries and elsewhere, broken down for narratives and total values over narratives Narratives Narrative Non-narrative Boundary Boundary Elsewhere Total 01 4 (36) 6 (55) 1 (9) (23) 8 (62) 2 (15) (13) 17 (74) 3 (13) (29) 11 (65) 1 (6) (0) 19 (66) 10 (34) (15) 25 (74) 4 (11) (11) 10 (53) 7 (36) (27) 11 (73) 0 (0) (20) 11 (73) 1 (7) (18) 31 (67) 7 (15) (17) 12 (67) 3 (16) (22) 8 (57) 3 (21) (27) 13 (59) 3 (14) (33) 16 (67) 0 (0) (20) 7 (70) 1 (10) (45) 3 (33) 2 (22) (26) 8 (42) 6 (32) 19 Total 68 (20) 216 (64) 54 (16) 338 The values in the above table should be considered with caution. Apparently, they suggest that pauses occur more often at non-narrative boundaries than at any other location (216 versus 122 pauses). This is true, if one takes into consideration the absolute numbers only. It is also true, however, that the number of boundaries that do not correspond to narrative boundaries in the data is much greater (510 versus 117). In other words, only 19% of all intonation boundaries in the narratives correspond to narrative boundaries. Therefore, the absolute numbers in Table 1 do not say much about the distribution of pauses in the data as a function of the type of boundary where they occur. In order to determine whether the type of boundary determines the occurrence of pause in narrative discourse, the distribution of pauses at narrative and non-narrative boundaries must be considered as a function of the actual number of each type of boundary. The proportion of occurrence and non-occurrence of pauses in narrative and non-narrative boundaries can be found in the pareto chart below (Figure 1):
4 Percent No Pause Pause 0 Narrative Boundary Boundary Type Non-Narrative Boundary Fig. 1. Distribution of pauses at narrative and non-narrative boundaries (pareto chart) It is clear now that a pattern in terms of occurrence of pause in relation to type of boundary does exist in the present data. In 65% of the time that a boundary corresponds to the end/beginning of a narrative section, a pause will occur. If the boundary is not a narrative boundary, this number drops to 43%. This difference is statistically significant (χ 2 =16.722, df=609, p<0.0001). Therefore, it s not always the case that an intonation unit boundary will determine the occurrence of a pause, as the literature proposes (Gee & Grosjean 1984; Rosenfield 1987). The occurrence of pause in discourse seems to be correlated with a higher-level segmentation. Table 2 below gives the total number of narrative boundaries and occurrence of pauses in all seventeen narratives, giving a more detailed look at the distribution of pauses as a function of the type of boundary in the data: Table 2. Total number of narrative boundaries and occurrence of pauses, broken down by narrative, and percentage values over narratives Narratives Boundaries Pauses %
5 Narratives Boundaries Pauses % Total Three narratives in the data (01, 08 and 14) are characterized by the presence of a pause at all narrative boundaries, as Table 2 above reveals. However, exceptions are also present. Narrative 05, for example, contains no pauses at narrative boundaries at all. Notwithstanding, what seems to be pertinent here is that with the exception of narratives 05 and 16, all the other narratives present a minimum of 50% of pause occurrence in the narrative boundary condition. These results indicate that pause occurrence is a reliable indicator of narrative boundary. The next step is to investigate whether pause duration also plays a role in the identifying of such boundary. 4. Pause duration as a narrative boundary signal A number of studies confirm the general hypothesis concerning pause duration as an indicator of boundaries between larger discourse units: the longer a pause is, the greater the chances that the place where it occurs coincides with a major discursive break (see, for example, , , , , , , , , , , , among others). However, none of these authors attempt to relate narrative structure to pausal phenomena using an independent framework of narrative analysis. Table 3 brings the mean values of duration for each narrative, as a function of the location where they occur. Table 3. Mean pause duration (standard deviation in parenthesis) at narrative boundaries, non-narrative boundaries and elsewhere, broken down for narratives and total values over narratives. The duration values are expressed in seconds Narratives Narrative Non-narrative Boundary Boundary Elsewhere Average (0.89) 0.77 (0.33) 0.43 (N/A) 0.94 (0.63) (0.18) 0.72 (0.27) 0.68 (0.18) 0.66 (0.25) (0.24) 0.79 (0.30) 0.65 (0.27) 0.77 (0.28) (0.44) 0.72 (0.38) 0.40 (N/A) 0.82 (0.43) 05 N/A 0.76 (0.43) 0.88 (0.24) 0.80 (0.37) (0.49) 0.95 (0.68) 0.54 (0.29) 0.99 (0.67) (0.99) 0.67 (0.24) 0.62 (0.33) 0.68 (0.27) (0.44) 0.74 (0.30) N/A 0.76 (0.33) (0.55) 0.85 (0.44) 0.62 (N/A) 0.86 (0.44) (0.11) 0.63 (0.32) 0.43 (0.15) 0.60 (0.28)
6 Narratives Narrative Non-narrative Boundary Boundary Elsewhere Average (0.11) 0.57 (0.28) 0.36 (0.05) 0.50 (0.25) (0.21) 0.62 (0.26) 0.92 (0.47) 0.74 (0.31) (0.57) 1.07 (0.78) 1.20 (0.68) 1.15 (0.70) (0.33) 0.55 (0.33) N/A 0.56 (0.32) (0.86) 0.47 (0.20) 0.59 (N/A) 0.56 (0.37) (0.37) 0.55 (0.03) 0.51 (0.03) 0.74 (0.34) (0.48) 0.77 (0.32) 0.73 (0.25) 0.79 (0.34) Average 0.92 (0.51) 0.74 (0.44) 0.68 (0.33) 0.76 (0.44) The mean duration of pauses occurring at narrative boundaries (0.92 s) differs significantly from those occurring at non-narrative boundaries (0.74 s). T-test result (t=-2.821, df=282, p<0.01) confirms this finding by showing a significant correlation between narrative boundary and longer pause duration. Again, a considerable amount of variation within narratives can be seen. Narratives 02, 03, 05, 10 and 11 do not follow the general pattern. The mean duration of pauses at narrative and non-narrative boundaries are the same for narratives 03 and 10, while narratives 02 and 11 have a mean pause duration longer at non-narrative boundaries than at narrative boundaries. As discussed above, narrative 05 does not present any pauses at all at narrative boundaries. This is of course an exception. Interestingly, narrative 05 is also inconsistent with the others in that it displays a high mean duration of pauses at non-boundary sites. Only narrative 12 shares this property. It should be pointed out, however, that while narrative 05 presents a large number of pauses at locations that do not correspond to any type of boundary (a total of 10 out of 29), narrative 12 has only a few (a total of 03 out of 14). Nonetheless, two of these pauses are also the longest in the whole narrative. Analyses of variance were carried out with pause duration as a dependent variable and narrative and participant as fixed factors. Results show significant effects for both narrative (F (16,283)=3.04, p<0.0001) and participant (F (7,283)=6.2866, p<0.001). Post-hoc tests (Tukey-Kramer multiple comparisons) for narrative show that narrative 13 differs significantly from narratives 10, 14, 15 and 11 and that narrative 06 also differ from the same ones except for 15. Note that both narratives (13 and 06) were produced by the same participant (08). As for the variable participant, Tukey-Kramer tests reveal that participant 08 differs significantly from participants 5, 7, 4, 3 and 2, while participant 1 differs significantly from participant 3 only. Table 2.6 below brings the actual mean duration of pause for each participant, along with standard deviations. Table 4. Mean pause duration and the corresponding standard deviation for each participant. Values are expressed in seconds Narrative Mean duration Sd
7 Participant 8 (narratives 01, 06 and 13) not only has the longest average pause duration, but also the largest standard deviation. Some of the pauses that are employed in the narratives produced by participant 8 were, in relation to the others, exceptionally long, contributing to the large standard deviation displayed in Table 4. Long pauses constitute, most of the time, what  calls semantic pauses. What is important to highlight is that both pause occurrence and pause duration prove to be significant predictors of narrative boundary. Narrative boundaries are characterized by the presence of a pause of longer duration, while non-narrative boundaries do not require the presence of a pause. When they occur, they tend to be shorter than those at narrative boundaries. 5. Conclusion It was hypothesized here, on the basis of the Labovian model of narrative analysis, that pausing reflects narrative structure longer pauses are more likely to occur at the end of a narrative section than elsewhere in a narrative. The analyses confirmed the hypotheses. It was demonstrated that pausing is a strong indicator of narrative boundary: at the end of a narrative section, storytellers often produce a pause of longer duration to indicate that a given chunk of information is completed and that a new chunk is about to begin. This is in accordance with the findings in both psycholinguistic research (see , , , , , among others) and computational linguistic research (see , [149, , , , , , among others). Longer pauses are extremely important in the production of speech for two reasons. First, they give the speaker time to adequately formulate the next group of information. Second, they are very significant in speech perception, because they help the audience to cognitively digest the input. References 1. Butterworth, B.: Evidence from pause in speech. In B. Butterworth. Language Production: Speech and Talk. Academic Press, London (1980) Brotherton, P.: Speaking and not speaking; Process for translating ideas into speech. In A. Siegman & S. Feldestein. Of Time and Speech. Lawrence Erlbaum, Hillsdale, N. J. (1979) Collier, R., Piyper, J. R. d. & Sanderman, A: Perceived prosodic boundaries and their phonetic correlates. Proceeding of the ARPA Workshop on Human Language Technology. Morgan Kaufman Publishers, Plainsboro, New Jersey, USA (1993). 4. Dalton, P. & Hardcastle, W. J.: Disorders of Fluency an Their Effects on Communication. London (1977). 5. Gee, J. P. & Grosjean, F.: Empirical evidence for narrative structure. Cognitive Science 8 (1984) Gee, J. P. & Kegl, J. A.: Narrative/story structure, pausing and ASL. Discourse Processes 9 (1983)
8 7. Glukhov, A. A.: Statistical analysis of speech pauses for Romance and Germanic languages. Soviet Physics. Acoustics 21 (1975) Goldman-Eisler, F.: Speech analysis and mental processes. Language and Speech 1 (1958) Goldman-Eisler, F.: The rate of changes in the rate of articulation. Language and Speech 4 (1961) Goldman-Eisler, F.: Psycholinguistics: experiments in spontaneous speech. Academic Press, London, New York (1968). 11. Goldman-Eisler, F. Pauses, clauses, sentences. Language and Speech 15 (1972) Grosz, B. & Hirschberg, J.: Some intonational characteristics of discourse structure. Proceeding of the International Conference on Spoken Language Processing, Banff (1992). 13. Hieke, A. E., Kowal, S. & O'Connell, D. C.: The trouble with "articulatory pauses". Language and Speech 26 (1983) Hirschberg, J. & Grosz, B.: Intonation features of local and global discourse structure. Proceeding of the DARPA Workshop on Spoken Language Systems, Arden House (1992). 15. Hirschberg, J., Nakatani, C. H. & Grosz, B. J.: Conveying discourse structure through intonation variation. Proceeding of the ESCA Workshop on Spoken Dialogue Systems: Theories and Applications. ESCA, Visgo, Denmark (1995). 16. Kowal, S. & O'Connell, D. C.: Some temporal aspects of stories told while or after watching a film. Bulletin of the Psychonomic Society 25(5) (1987) Kowal, S., O'Connell, D. C. & Sabin, E. J.: Development of temporal patterning and vocal hesitation in spontaneous narratives. Journal of Psycholinguistic Research 4 (1975) Kowal, S., Wiese, S. & O'Connell, D.: The use of time in storytelling. Language and Speech 26(4) (1983) Labov, W.: The transformation of experience in narrative syntax. Language in the inner City. University of Pennsylvania Press, Philadelphia (1972) Levin, H., Schaffer, C. & Snow, C.: The Prosodic and Paralinguistic Features of Reading and Telling Stories. Language and Speech 25(1) (1982) Levin, H., Silverman, I. & Ford, B.: Hesitations in children's speech during explanation and description. Journal of Verbal Learning and Verbal Behavior 6 (1965) Litman, D. J. & Passonneau, R. J.: Empirical evidence for intention-based discourse segmentation. Proceeding of the ACL Workshop on Intentionality and Structure in Discourse Relations (1993). 23. Maclay, H. & Osgood, C. E.: Hesitation phenomena in spontaneous English speech. Word 15 (1959) Nakatani, C.: Accenting on pronouns and proper names in spontaneous narratives. Proceeding of the ESCA Workshop on Prosody, Lund, Sweden (1993). 25. Nakatani, C. H. & Hirschberg, J.: Discourse structure in spoken language: Studies on speech corpora. Proceeding of the AAAI Symposium Series: Empirical Methods in Discourse Interpretation and Generation (1995). 26. Oliveira, M.: Prosodic Features in Spontaneous Narratives. Ph.D. Thesis, Simon Fraser University (2000).
9 27. O'Connell, D. C. & Kowal, S.: Pausology. In W. A. Sedelow & S. Y. Sedelow. Computers in Language Research 2. Mouton Publishers, Berlin, New York, Amsterdam (1983) Pakosz, M. & Flashner, V.: Prosodic features and narrative strategies. Papers and studies in contrastive linguistics 24 (1988) Passonneau, R. J. & Litman, D. J. : Intention-based segmentation: Human reliability and correlation with linguistic cues. Proceeding of the 31st Annual Meeting of the Association for Computational Linguistics (ACL-93), Columbus, Ohio (1993). 30. Passonneau, R. J. & Litman, D. J.: Discourse Segmentation by Human and Automated Means. Computational Linguistics 23(1) (1997) Rosenfield, B.: Pauses in Oral and written Narratives. Boston University, Boston (1987). 32. Siegman, A. & Feldestein, S. (eds.): Of Time and Speech. Lawrence Erlbaum, Hillsdale, N. J. (1979). 33. Siegman, A. W. & Pope, B.: Ambiguity and verbal fluency in the TAT. Journal of Consulting Psychology 30 (1966) Stenström, A.-B.: Pauses in monologue and dialogue. In E. Svartvik. The London-Lund Corpus of Spoken English. Description and Research. Lund University Press, Lund (1990) Wolfson, N.: Speech events and natural speech. Language in Society 5 (1976)