Examination of the Spanish Vowels Produced by Spanish-English Bilingual Children

ABSTRACT. This article presents the findings of a cross-sectional study of the Spanish vowel productions of Spanish-English bilingual children. The data set is based on a picture sorting task conducted with 20 children, aged 6 to 14, in pairs. An acoustic examination of F1 and F2 values was carried out on multiple tokens of each vowel for each child. In general, the findings indicate that the vowel space of the bilingual children more closely resembles that reported for bilingual adults than that of monolingual adults. With respect to changes according to age, older learners produced vowels in a smaller vowel space than younger learners; in addition, while the younger learners did not demonstrate any centralization of unstressed vowels, older learners did. 1. INTRODUCTION. Work on phonological variation in Spanish has focused primarily on consonants as it has been understood that vowels are produced similarly across the dialects of Spanish (Navarro Tomas 1977, Stockwell and Bowen 1965, Zamora and Guitart 1982). However, recent work on the vowels of Spanish speakers in the US Southwest has shown that they have different acoustic features than those reported for other dialect regions (Willis 2005). Although this particular dialect is in contact with English, Willis did not observe English influence in the form of centralization of unstressed /a/. The results of Gildersleeve-Neumann et al (2009) differ from those of Willis in that the Spanish vowel productions of the Spanish-English bilingual children evidenced the influence of English within 8 months of initial exposure to English. Gildersleeve-Neumann et al (2009:268) noted 'that vowels are particularly vulnerable in Spanish-learning children . because of the potential reorganization created by exposure to a more complex English vowel system'. These two studies present conflicting results, which could potentially be explained by the different ages of the subjects and the vast difference in amount of exposure to English. This study will address the acoustic characteristics of the Spanish vowels of Spanish-English bilinguals in the US Southwest, in addition to systematically attending to the question of stress. It also provides much needed information about the acoustic characteristics of vowel productions of Spanish-speaking children. The organization of this paper is as follows: Section 2 reviews work on Spanish vowels and child vowel production. Section 3 details the experimental methodology, describing subjects, the task, and analysis techniques. Results are presented in Section 4, followed by a discussion of the findings in Section 5. Finally, Section 6 presents conclusions and their potential implications for the field and future research. 2. PREVIOUS RESEARCH. 2.1 SPANISH VOWELS. Vowels, unlike consonants, are produced by an unobstructed passage of air through the vocal tract. The defining feature of vowels, vowel quality, is the result of the shape the resonating cavity, or vocal tract, during their production. The shape can be affected by the position of the tongue in the mouth, the position of the lips, and the position of the soft palate. The resonances of the vocal tract are called formants which appear as dark bands of energy on spectrograms. The specific frequencies at which formants occur vary from vowel to vowel and provide each with its distinctive quality. The first formant (F1), second formant (F2), and third formant (F3) are used across languages to distinguish vowels; however, in Spanish, typically only F1 and F2 are used as F3 is non-distinctive in this language. The primary articulatory correlate of F1 is tongue height; an inverse relationship exists between tongue height and F1 frequency. The higher the tongue position in the mouth, the lower the F1 value, and the lower the position of the tongue, the higher the F1 value. Although F2 values are affected by the degree of lip rounding, the primary correlate of F2 is tongue backness; lower F2 values are associated with a more back tongue position, and higher F2 values are associated with a more fronted tongue position. …