Present Experiment

1. Coarticulatory Timing and Lexical Effects on Vowel Nasalization in English: an Aerodynamic Study Jason Bishop University of California, Los Angeles Introduction Results: Within VNT and VND Lexical Effects: Neighborhoods • In English, vowels show significant nasalization when preceding a nasal consonant. The extent of this coarticulation, however, depends on other aspects of the phonetic context. For example, in (C)VNC sequences, nasalization is more extensive when: • initial C is an aspirated stop, or if NC are tautosyllabic (Cohn 1995). • V is stressed (Krakow 1993). • C is voiceless rather than voiced (Malécot 1960). Beddor (2007) suggests the difference between a voiced C context (VND) and voiceless C context (VNT) is not due to more nasalization as such, but to the earlier onset of velum lowering when the oral articulation for N is shorter: 2. Neighborhood size and vowel nasalization positively correlated (R2 = .15 – .49) 2. N duration is a better predictor of Ṽ duration within voicing contexts: Word List Less Nasalization Constant-sized velum-lowering gesture begins later when N is longer, overlapping less with vowel Figure 3. Vowel nasalization and nasal consonant duration in a voiceless obstruent context. R2 for trend lines = .61(Speaker 1), .16(Speaker 2), .25(Speaker 3), .10(Speaker 4). Figure 4. Vowel nasalization and nasal consonant duration in a voiced obstruent context. R2 for trend lines = .29(Speaker 1), .28(Speaker 2) .23(Speaker 3), .37(Speaker 4). More Nasalization Constant-sized velum-lowering gesture begins earlier when N is shorter, overlapping more extensively with vowel Summary  Within both the voiced and voiceless context, the duration of N accounted for considerable amounts of the variation in Ṽ; not true when voicing contexts were considerable together.  This differs from what is reported in Beddor 2007, where the strongest relationship was found across voicing contexts. Figure 6. Proportion vowel nasalized (Ṽ/Vtotal) and neighborhood size (each point represents average values over three repetitions of each of nine tokens). Beddor (2007) presents acoustic evidence from VNC productions of 5 speakers of American English that this trading relationship between the durations of nasal consonants (N) and the duration of coarticulatory vowel nasalization (Ṽ), holds (R2 ranging from .27 to .45). 3. N and Ṽ: inversely correlated for lexically easy words, unrelated or positively correlated for lexically difficult tokens Present Experiment Lexical Effects: Frequency Easy Difficult Goals 1.) Corroborate the findings in Beddor 2007 with aerodynamic data. 2.) Examine possible lexical effects as an additional source of variation in extent of coarticulatory vowel nasalization. Methods  4 speakers of American English (2 male, 2 female; ages 21 – 28)  Speakers read (C)VNC tokens embedded in the carrier sentence “Please say ______ with me”.  Oral and nasal airflow collected simultaneously with audio recordings. Variables  Duration of the nasal consonant (N)  Duration of significant nasal airflow over the vowel (Ṽ) (i.e., nasal flow above the levels present in non-nasal context controls –e.g., sped for spend)  Proportion of the vowel with significant nasal airflow (duration of significant nasal airflow over the vowel / total duration of vowel)  Scarborough (2004) measured anticipatory nasal coarticulation in two lexical confusability conditions, finding more extensively nasalized vowels in more confusable or, here, lexically “difficult” words: Easy (or high R : high frequency within sparse phonological neighborhoods) Difficult (or low R : low frequency within dense phonological neighborhoods) Three Questions 1.) Does lexical frequency (independent of neighborhood size/lexical difficulty) influence the relation between N and Ṽ ? 2.) Does neighborhood size correlate with degree of nasalization ? 3.) How does lexical difficulty influence the relation between N and Ṽ ?  Subsets of the production data with the relevant lexical properties were examined to address these questions.  Lexical statistics were taken from the Washington University Speech and Hearing Lab Neighborhood Database. Word List Easy Difficult 1. N and Ṽ: trend towards inverse correlation for high frequency, positive correlation for low frequency tokens High Frequency Low Frequency 1000 ml/s Word List 500 ml/s High Frequency Figure 7. Vowel nasalization and nasal consonant duration for lexically easy and difficult words (high and low R, respectively). Three repetitions of 6 tokens plotted for each lexical type). Figure 1. From top to bottom channels: Audio, oral airflow, nasal airflow for the sentence “Please say bend with me.” Black dotted line shows duration of the vowel with significant nasal flow; red dash dot line shows the duration of the nasal consonant. Zero nasal flow is referenced to nasal flow during the vowel of non-nasal [bɛt]. Conclusion Results: Across Voicing Context  The results presented here are in general agreement with those in Scarborough 2004:  Speakers produced more, not less, coarticulation for tokens from denser phonological neighborhoods.  Further, they have implications for patterns of gestural alignment discussed in Beddor 2007:  A tendency to decrease vowel nasalization in the presence of a longer nasal consonant, as predicted by Beddor, is apparent in the productions of these 4 speakers.  But: this effect is restricted to just those lexical conditions expected to be easy for listeners: high-frequency words and words of a high frequency within sparse neighborhoods.  Such findings are highly suggestive of what we should expect in a more listener-oriented communication task (more coarticulation for low frequency/difficult words regardless of the duration of the nasal consonant), and as such are very difficult to understand under a view of coarticulation as reduction (e.g., Thatham & Morton 2006). 1. Evidence for an inverse relationship not found across voicing contexts: Low Frequency References Figure 5. Vowel nasalization and nasal consonant duration for high and low frequency subsets of the tokens (three repetitions of 8 tokens plotted for each frequency condition). Beddor, P. (2007). Nasals and nasalization: the relation between segmental and coarticulatory timing. Proceedings of the 16th International Congress of Phonetic Sciences, 249-254. Cohn, A. (1990). Phonetic and phonological rules of nasalization. UCLA Working Papers in Phonetics 76, 1 – 224. Krakow, R. (1993). Nonsegmental influences in velum movement patterns: syllables, sentences, stress, and speaking rate. In Huffman, M. & Krakow, R. (eds.): Nasals, Nasalization, and the Velum. New York: Academic Press, 87 – 113. Malécot, A. (1960). Vowels nasality as a distinctive feature in American English. Language 36, 222 – 229. Tatham, M. & Morton, K. (2006). Speech production and perception. New York: Palgrave. Figure 2. Scatterplot showing vowel nasalization as a function of the duration of the nasal consonant for (C)VNC test words (across voicing contexts for C). Although the trend is in the direction of an inverse relationship, the duration of N accounts for very little of the variation in Ṽ. R2 = .03(Speaker 1), .05(Speaker 2), .02(Speaker 3), .05(Speaker 4).