Is there a functional basis for certain commonly observed linguistic sound patterns?

1. Evidence of a Production Basis for Front/Back Vowel HarmonyJennifer Cole, Gary Dell, Alina Khasanova University of Illinois at Urbana-Champaign • Results: Experiment 1, Front/Back Harmony • Mean production times are significantly lower in the harmony condition with the consonant /b/ (t=1.865, p< 0.05). • Mean error rates are significantly lower in the harmony condition with all consonants: /b/ (t=1.721, p<0.05), /k/ (t=3.089, p<0.01) and /g/ (t=1.877, p<0.05). • Conclusion: Front/Back vowel harmony facilitates fast speech production, reducing the incidence of errors. • Is this an effect on speech articulation or speech planning? • Hypothesis: If vowel harmony facilitates speech planning, similar facilitation effects should be observed for vowel harmonies involving different vowel features. • Experiment II: Height Vowel Harmony • Method and subjectssame as Experiment I. • Materials: nonsense sequences of the form CVd.hVd the CVd.hVd, with V chosen from the set of lax vowels / ,  / (high) and / ,  / (non-high), and C chosen from /b,k,g/. Tense vowels were rejected to avoid the height contour of the tense diphthongs [ej, ow]. • Harmonic sequences: e.g., goodhid the gedhud (hi-hi – nonhi-nonhi) • Disharmonic sequences: e.g., bedhood the bidhud (nonhi-hi – hi-nonhi) • Results: No harmony effects observed in production times or error rates. • Conclusion: the failure of height harmony to reduce errors in fast speech suggests that the harmony effect observed with back/front harmony is specific to that dimension of vowel articulation. Together, these findings suggest that vowel harmony reduces the complexity of speech articulation, and does not result in a general facilitation of speech planning. • Implications for speech planning: facilitation effects occur only with shared structural features (e.g., syllable or metrical structure), but do not extend to shared features of segment quality. • Is there a functional basis for certain commonly observed linguistic sound patterns? • Are phonological constraints innate or learned from primary speech experience? • Is there a special status for sound patterns that facilitate the acts of speaking and comprehension? • How phonological constraints might impact speech: • reduce articulatory complexity increase perceptual salience • optimize lexical access optimize speech planning • Possible functional bases for vowel harmony • perceptual: assimilatory sound patterns may result from listeners’ “misperception” of coarticulated vowel sequences (Ohala 1993; Beddor et al 1999). Vowel harmony may thus reduce perceptual ambiguity. • articulatory: the occurrence of shared features/gestures increases articulatory economy (Lindblom 1983). • speech planning: repeating phonological structure facilitates speech planning, as structures are ‘recycled’ in the planning of successive chunks of speech. • Our Hypothesis: Vowel harmony, where vowel features are shared across successive vowels, may result in an economy of speech articulation or planning, manifesting in speech that is faster and/or less errorful. • Testing the hypothesis with fast speech experiments • Experiment I: Front/Back Vowel Harmony • Method: Subjects repeat sequences of nonsense syllables as many times as possible in five seconds, while maintaining accuracy in pronunciation. Nonsense syllables are presented on a computer screen in a sequence on a single line of text. The subject rehearses the sequence aloud once or twice and is prompted to begin producing the fast repeated speech at the sound of a tone. Another tone signals the end of the trial. • Subjects: 26 monolingual native English users, undergrads at UIUC from the Chicago area, with self-reported normal speech and hearing. • Materials: Nonsense sequences of the form CVCV the CVCV. • C was selected from /b,g,k/. • V was selected from /i:, u:, e:, o:/, phonetically [ij, uw, ej, ow]. • The two vowels within each CVCV word were distinct. • Example, presented orthographically: beeboo the baybo • The harmony condition: sequences where each CVCV word contained only front /i:, e:/ or only back /u:, o:/ vowels, e.g., beebay the boboo, or boboo the boobo. The four sequences of identical vowels were excluded from the study (e.g., beebee). Total number of harmonic CVCV-CVCV sequences: (4x1x4x1) vowel sequences = 16; 16 x 3 consonants = 48. • The disharmony condition: sequences where each CVCV word contained vowels that disagreed in their front/back feature, e.g., bobee the boobee. Total number of disharmonic CVCV-CVCV sequences: (4x2x4x2) vowel sequences = 64. These were divided into 4 groups of 16, each balanced for frequency of individual vowels and vowel combinations. Subjects were quasi-randomly assigned to each disharmony group. Total disharmonic CVCV-CVCV sequences per set: 16 x 3 consonants = 48. • Both words in a sequence were in the same harmony condition; there were no harmonic-disharmonic mixed sequences. The materials set was balanced for the occurrence of each vowel individually, and for vowel combinations within the word. • Coding: Speech data was recorded onto tape and coded for errors and number of syllables per trial by two independent coders. Coder agreement was 90.58% and highly correlated (R2=.951). Data from two subjects was eliminated due to error rates over 50%. • Analysis: 1-tailedt-tests were used to compare mean syllable production times and mean error rates for harmonic and disharmonic conditions within each consonant condition. • Mean syllable production time based on production time for error-free trials: 5000 ms./ # of syllables. • Mean error rate, as a percent of total trials. • Sevald et al (1995) find that subjects produce sequences of nonsense syllables faster when the syllables have a common syllable structure, despite differences in the segmental content of those syllables. They attribute this effect to an economy at the level of speech planning. References: Beddor, P., Krakow, R. and S. Lindemann. 1999. Patterns of perceptual compensation and their phonological consequences. In E. Hume and K. Johnson (eds.), The Role of Speech Perception in Phonology, pp. 55-78. New York: Academic Press.  Sevald, C., Dell, G. and J. Cole. 1995. Syllable structure in speech production: are syllables chunks or schemas? Journal of Memory and Language, 34:807-820.  Lindblom, B. 1983. Economy of speech gestures. In P. MacNeilage (ed.) Speech Production, pp. 217-246. New York: Springer.  Ohala, J. 1993. Coarticulation and phonology. Language and Speech, 36:155-170.