Results ISI Variance in STP Corpus ISI Variance in BU Corpus

1. Stress Regularity in Language • Stress patterns reflect a preference for an even spacing of stresses. While the conventional distinction between “stress-timed” and “syllable-timed” languages has not been supported (Dauer 1983), most recent authors agree that stress patterns in most languages tend toward regularity (Liberman & Prince 1977; Selkirk 1984; Ladefoged 1993; Hayes 1995). • Two factors may contribute to stress regularity: • Distributional stress regularity refers to regularity in the stress pattern itself (S = stressed, U = unstressed): • S U S U S U S U S U S U (regular) • S S U U U S U S S U U U (irregular) • Durational stress regularity refers to variations in syllable duration than enhance regularity (Beckman et al. 1990). • Distributional stress regularity depends on three factors: • Lexical stress patterning: Regularity in stress patterns within • words. Example: Stress shift within stems as affixes are • added, e.g. infést / ínfestátion (Liberman & Prince 1977). • Interlexical stress patterning: Words may be chosen and • combined in ways that enhance regularity. Example: • Disyllabic nouns and verbs are used in different stress • contexts which promote regularity in combination with • their typical word-internal stress patterns (nouns are usually • trochaic, verbs are usually iambic) (Kelly & Bock 1988). • Contextual stress patterning: Normal lexical stress patterns • may be adjusted to facilitate stress regularity. Example: • “stress clash avoidance” phenomena such as thirtéen / • thírteen mén (Hayes 1995). • Two Questions • 1. To what degree does English actually reflect distributional stress regularity? • 2. How much of this regularity is due to lexical, interlexical, and contextual stress patterning? • Our approach is to take naturally-occurring language data annotated with stress information, measure its distributional regularity, and then manipulate the text to isolate the effects of lexical, interlexical, and contextual stress patterning. • Corpora • Two phonetically annotated corpora were used, both manually labeled with stress information: • The Switchboard Transcription Project (STP) (Greenberg 1997): Telephone conversations. 644 (usable) utterances, 5916 syllables. Syllables were marked 1, 0.5, or 0 to indicate stress; here, 1 and 0.5 are defined as stressed and 0 as unstressed. • The BU Radio News Corpus (Ostendorf et al. 1995): Radio news stories. 98 (usable) sentences, 2850 syllables. Stressed vowels were marked with 1; unmarked vowels were taken as unstressed syllables. Results ISI Variance in STP Corpus ISI Variance in BU Corpus * p < .01. ** p < .001. *** p < .0001. 1A randomization of the annotated or citation-form stress pattern, as appropriate. Conclusions 1. English reflects a strong tendency towards distributional stress regularity. 2. Lexical and interlexical patterning both contribute significantly to regularity. 3. Contextual stress patterning does not contribute to stress regularity; contextual adjustments to stress tend to reduce regularity rather than increasing it. References Beckman, M. E., Swora, M. G., Rauschenberg, J., and de Jong, K. (1990). Stress shift, stress clash, and polysyllabic shortening in a prosodically annotated discourse. Proceedings of ICSLP. Dauer, R. M. (1983). Stress-timing and syllable-timing reanalyzed. Journal of Phonetics 11: 51-62. Greenberg, S. (1997). The Switchboard Transcription Project. 1996 Large Vocabulary Continuous Speech Recognition Summer Research Workshop Technical Report Series, Research Report #24. Baltimore, MD: Center for Language and Speech Processing, Johns Hopkins University, Baltimore, MD. Hayes, B. (1995). Metrical stress theory. University of Chicago Press, Chicago. Kelly, M. H., and Bock, J. K. (1988). Stress in time. Journal of Experimental Psychology: Human Perception and Performance 14: 389-403. Ladefoged, P. (1993). A course in phonetics, Harcourt Brace, Fort Worth. Liberman, M., and Prince, A. (1977). On stress and linguistic rhythm. Linguistic Inquiry 8: 249-336. Ostendorf, M., Price, P. J., and Shattuck-Hufnagel, S. (1995). The Boston University Radio News Corpus. Boston University Technical Report No. ECS-95-001. Selkirk, E. (1984). Phonology and syntax: The relation between sound and structure, MIT Press, Cambridge. Distributional Stress Regularity: A Corpus Study David Temperley, Eastman School of Music, University of Rochester Analysis (with an example) 1. Stress regularity of the original text. This was measured as the variance of interstress intervals (ISIs) in the original annotated data. Example sentence from BU corpus (showing annotated stress pattern): 0 1 0 1 0 0 0 1 0 0 1 0 1 0 0 it functions like an electronic probation officer inter-stress intervals = 2 4 3 2 ISI variance = 0.69 2.Random permutations. To examine the regularity of the above stress pattern, we compare its ISI variance to that of a random permutation of the syllables: 0 0 0 1 0 0 0 0 0 1 0 1 0 1 1 ISI variance = 3.69 3.Lexical stress patterning. We measure the effect of lexical stress patterning by replacing the annotated stress patterns with citation-form stress patterns taken from a phonological dictionary (the CMU Pronunciation Dictionary, version 6) and randomizing the order of the words: 0 1 0 0 0 1 1 0 1 0 0 0 0 1 0 probation an electronic officer like it functions ISI variance: 2.50 Comparing this ISI variance to that of a random permutation of the syllables (step 2 above) shows the effect of lexical stress patterning. 4. Interlexical stress patterning. We measure the effect of interlexical patterning by using citation-form stress patterns for the words but retaining the original word order. 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 it functions like an electronic probation officer ISI variance = 2.19 Comparing the ISI variance of this to that of a citation-form, random-word-order pattern (step 3) shows the effect of interlexical stress patterning. 5.Contextual stress patterning. We can now see the effect of contextual stress patterning simply by comparing the variance of the original annotated stress pattern (step 1) to that of the citation-form, original-word-order pattern (step 4). ISI variance of citation-form pattern = 2.19 ISI variance of annotated stress pattern = 0.69