The statistical analysis of acoustic correlates of speech rhythm D enise D uarte* U niversidade Federalde G oiás and U niversidade de São Paulo A ntonio G alves U niversidade de São Paulo N ancy L. G arcia U niversidade Estadualde C am pinas R icardo M aronna* U niversidad de La Plata http://w ww.im e.usp.br/~tycho * : authorsw ho presented the paper
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The statistical analysis of acoustic correlates of speech rhythm.
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The statistical analysis of acoustic correlates of speech rhythm
Denise Duarte*Universidade Federal de Goiásand Universidade de São Paulo
Antonio Galves Universidade de São Paulo
Nancy L. GarciaUniversidade Estadual de Campinas
Ricardo Maronna*Universidad de La Plata
http://www.ime.usp.br/~tycho* : authors who presented the paper
1. Introduction
Data description: two corpora
“20 sentences”: 20 sentences spoken three times by two female native speakers of BP and EP ( segmented by Flaviane R. Fernandes and Janaisa M. Viscardi)
“RNM”: 20 sentences of each of : English, Polish, Dutch, French, Spanish, Catalan, Italian, Japanese 5 sentences uttered by each of 4 female speakers
Purposes
Apply the RNM approach to the enlarged data set. Present alternative descriptive statistical measures Analize the effect of dropping the last vocalic
interval of each sentence. Introduce a probalility model for duration, which
allows for improved descriptions and hypothesis testing
Use this model to give statistical support to the rhythmic class hypothesis
The RNM statistics
For each sentence of the corpus the following are computed:
DC, DV= standard deviation for vocalic and consonantal intervals
To test the model, we first tested (1) and (2) by means of the Likelihood Ratio Test, which yielded a p-value of 0.91, which means that the equality of s's within rhythmic classes is highly compatible with the data ( a small p-value indicates rejection).
Then we tested the null hypothesis that some of s1 ,
s2, s3 are equal, which was rejected with a p-value
of 0.0012, thus giving statistical evidence that the three are different.
Acknowledgments
We want to thank Franck Ramus, Marina Nespor and Jacques Mehler, who generously made their unpublished data avalaible to us.
We also thank Janaisa Viscardi and Flaviane Fernandes for the segmentation of the acoustic
data
The “20 sentences” corpus
The following sentences of the corpus 20 sentences were considered in the statistical analysis. The choice was based on the quality of acoustic signal and to avoid dubious cases of labeling.
1. A moderniza₤₧o foi satisfatória. 5. A falta de moderniza₤₧o ₫ catastrófica.6. O trabalho da pesquisadora foi publicado.8. O governador aceitou a moderniza₤₧o.9. A falta de autoridade foi alarmante.11. A catalogadora compreendeu o trabalho da pesquisadora.12. A professora discutiu a gramaticalidade.15. A procura da gramaticalidade ₫ o nosso objetivo.16. A pesquisadora perdeu autoridade.18. A autoridade cabe ao governador.20. A gramaticalidade das frases foi conseguida.
Grants supporting the research
FAPESP grant n. 98/3382-0 (Projeto Temático Rhythmic patterns, parameter setting and language change ) PRONEX grant 66.2177/1996-6 (Núcleo de Excel₨ncia Critical phenomena in probability and stochastic processes)
CNPq grant 465928/2000-5 (Probabilistic tools for pattern identification applied to linguistics)
Related papers and referencesAbercrombie, D. (1967). Elements of general phonetics. Chicago: Aldine.
Grabe, E. and Low, E., L. (2000) Acoustic correlates in rhythmic class. Paper presented at the 7th conference on laboratory phonology, Nijmegen.
Lloyd, J. (1940) Speech signal in telephony. London.
Mehler, J., Jusczyk, P., Dehane-Lambertz, G., Bertoncini, N. And Amiel-Tison, C. (1988) A percursor of language acquisition in young infants. Cognition 29: 143-178.
Nazzi, T., Bertoncini, N. and Mehler, J. ( 1998) Language discrimination by newborns towads an understanding of the role of the rhythm. Journal of experimental psychology: human perception and perfomance 24 (3): 756-766.
Nespor, M. (1990) On the rhythm parameter in phonology. Logical issues in language acquisition, Iggy Roca , 157-175.
Ramus, F. And Mehler, J. ( 1999). Language acquisition with suprasegmental cues: a study based on speecch resynthesis. JASA 105: 512-521.
Ramus, F., Nespor, M. and Mehler (1999) Correlates of linguistic rhythm in speech. Cognition 73: 265-292.
Frota, S. and Vigário, M.(2001) On the correlates of rhythm distinctions: the European/ Brazilian Portuguese case. To be published in Probus.
Appendix: the meaning of a p-valueConsider the situation of testing a statistical hypothesis: To
fix ideas, suppose that we have samples from two populations, and we want to test the hypothesis that both have the same (unknown) mean. Of course, even if the hypothesis is true, the two sample means will be different, due to sampling variability.
To test the hypothesis, we compute a number T from our data (the so-called “test statistics”) which measures the discrepancy between the data and the hypothesis. In our example T will depend on the differences between the sample means. If T is very large, we have a statistical evidence against the hypothesis. What is a rational definition of “large”?
Suppose our data yields T=3.5; and that we compute
the probability p that, if the hypothesis is true, we obtain a value of T greater than 3.5. This the so-called “p-value” of the test. If, say, p= 0.002, this means that, if the means are equal, we would be observing an exceptionally large value ( since a
larger one is observed only with probability 0.2%); Thus we would have grounds to reject the