Variation in Acoustic Vowel Space in Dholuo Dialects: A Dialectical Study of KSN and B-U Dholuo Vowels of Kisumu and Siaya Counties in Kenya

Purpose: - This linguistic study investigates the acoustic variation of Kisumu South Nyanza (KSN) and Boro Ukwala (B-U) Dholuo vowels in acoustic vowel space. Methodology: - A combination of field recordings from ten key respondents and acoustic analysis using Praat version 6.0.43 to extract vowel duration, F1, F2 and F3 values. The researcher compared the formant frequencies from each vowel frame, ensuring vowel quality is maintained during the process of data collection. The sounds were recorded using Praat in a quiet environment in respondents’ homes. The respondents produced a natural speech in the process. A carrier sentence that contained the required tokens was presented, recordings made and stored in the form of memory stick voice. The tokens were presented in CVCV structure in the environment of /h/, /t/, /p/ and /k/ voiceless sounds. The group mean formant values were normalized using Lobanov. Source Filter Theory was employed in vowel production and Dialectology Theory too to determine sounds and linguistic variations in Dholuo language. Findings: - The researcher realized notable differences in the structure of KSN and B-U acoustic vowel space with the adjacent vowels of B-U and KSN maximally and minimally dispersed from each other. In the adjacent KSN and B-U Dholuo vowels [u,ʊ] and [o,ɔ], differences were palpable, with B-U vowel [ʊ] most back, KSN vowel [u] minimally adjusted to the centre, central KSN back vowel [o] most back with B-U central back vowel [ɔ] adjusted to the centre. Minimal differences was observed in B-U and KSN adjacent vowels [i ,I], ], [e,ɛ] and [a,ɑ] with relatively low dispersion rates. Unique Contribution to Theory, Practice and Policy: - Acoustic vowel space variation in languages including Dholuo, enhances the understanding of phonetic and phonological characteristics of Dholuo dialect. It promotes neural and cognitive processes involved in speech production and perception including an effective identification of patterns and trends that informs Dholuo evolution and development. Speakers can be able to adjust their vowel sounds to accommodate the acoustic demands of certain environments and be aware of the acoustic differences between dialects that results in varied speech. This research will undoubtedly help in developing policies that promote language diversity and inclusivity in shaping language in communication.