Language and Speech

Two studies explored the processing of ambiguous sentences like Bill took chips to the party and Susan to the game, which may be assigned a gapping (Susan took chips) or a nongapping structure (Bill took Susan). The central question was what factors affect the ultimate interpretive preferences for these sentences. In a written questionnaire, sentences with greater parallelism between arguments in the positions of Bill and Susan received more gapping responses, though an overall bias toward the non gapping structure was seen. An auditory comprehension study showed that prosodic parallels between arguments also affected interpretation. In both experiments parallelism played a significant role in determiningan interpretation, but the simpler structure, the nongapping structure, was preferred overall.

A computational model of emergent syllable systems is developed based on a set of functional constraints on syllable systems and the assumption that language structure emerges through cumulative change over time. The constraints were derived from general communicative factors as well as from the phonetic principles of perceptual distinctiveness and articulatory ease. Through evolutionary optimization, the model generated mock vocabularies optimized for the given constraints. Several simulations were run to understand how these constraints might define the emergence of universals and variation in complex sound systems. The predictions were that(1) CV syllables would be highly frequent in all vocabularies evolved under the constraints; (2) syllables with consonant clusters, consonant codas,and vowel onsets would occur much less frequently; (3) a relationship would exist between the number of syllable types in a vocabulary and the average word length in the vocabulary; (4) different syllable types would emerge according to, what we termed, an iterative principle of syllable structure and their frequency would be directly related to their complexity; and(5) categorical differences would emerge between vocabularies evolved under the same constraints. Simulation results confirmed these predictions and provided novel insights into why regularities and differences may occur across languages. Specifically, the model suggested that both language universals and variation are consistent with a set of functional constraints that are fixed relative to one another. Language universals reflect underlying constraints on the system and language variation represents the many different and equally-good solutions to the unique problem defined by these constraints.

Fricative spectral data are compared with articulatory data from electropalatographic (EPG) recordings in an investigation of coarticulatory effects on the acoustic signal. Data were taken from CV tokens produced by four female speakers of Australian English. Results are presented for the coronal fricatives /θ s ∫ ð z 3/in seven monophthong vowel contexts. The analysis consists of a comparison of spectral centre of gravity (COG) with EPG centre of gravity measured along the horizontal dimension. The correlation between the articulatory and the acoustic datais quitehigh. Overall, the sibilant fricatives show very little variability in production, while the nonsibilant dental shows a good deal of variability. This is reflected in the spectral output. It is also shown that the alveolar sibilants show more effectfrom vowel context than do the postalveolar sibilants. These results are interpreted as showing that coarticulatory resistance is indeed greater for sibilant fricatives, but that degree of tongue body raising inherent in the fricative's production must also be taken into account. The results for overall variability are discussed with reference to the Hyper- and Hypo- and Quantal Theories of speech production.It is suggested that sibilant fricatives do not lend themselves to the articulatory imprecision which, according to these theories, characterizes perceptually salient, and typologically common, speech sounds.

Four phoneme-detection studies tested the conclusion from recent research that spoken-language processing is inhibited by violation of obligatory assimilation processes in the listeners' native language. In Experiment 1, native listeners of German detected a target fricative in monosyllabic Dutch nonwords, half of which violated progressive German fricative place assimilation. In contrast to the earlier findings, listeners detected the fricative more quickly when assimilation was violated than when no violation occurred. This difference was not due to purely acoustic factors, since in Experiment 2 native Dutch listeners, presented with the same materials, showed no such effect. In Experiment 3, German listeners again detected the fricative more quickly when violation occurred in both monosyllabic and bisyllabic native nonwords, further ruling out explanations based on non-native input or on syllable structure. Finally Experiment 4 tested whether the direction in which the rule operates (progressive or regressive) controls the direction of the effect on phoneme detection responses. When regressive German place assimilation for nasals was violated, German listeners detected stops more slowly, exactly as had been observed in previous studies of regressive assimilation. It is argued that a combination of low expectations in progressive assimilation and novel popout causes facilitation of processing, whereas not fulfilling high expectations in regressive assimilation causes inhibition.