The Prosody of Nigerian English

Nigerian English is a variety of English which has often been suggested to differ significantly from other varieties of English, especially in the area of prosody. This paper analyses the prosody of Nigerian English and compares it to the prosody of British English and three West African tone languages. Read and semi-spontaneous speech was analysed acoustically. Significant differences were found in speech rhythm, where Nigerian English groups between the West African languages Anyi, Ega and Ibibio and British English. Furthermore, Nigerian English syllable structure is different from that of British English, and the tonal structure of Nigerian English is more similar to that of a tone language than an intonation language. 1. Prosody and Language Typology Typological studies of languages have paid more attention to syntax and morphology than phonology, but research on the typology of the prosodic systems of the languages of the world is increasing [9],[10],[5],[13]. Cross-linguistic comparison in prosody is often done on the basis of speech rhythm, tonal structure and syllable structure. In the area of speech rhythm, languages have traditionally been divided into stress-timed and syllable-timed [16],[1]. Speech rhythm was understood to be a periodic recurrence of events. In syllabletimed languages such as French and Yoruba syllables were assumed to be equal in length. Stress-timed languages such as English or Polish, in contrast, were postulated to have regular recurring stress beats. No acoustic basis for either isochrony of stresses in stress-timed languages or equal length of syllables in syllable-timed languages was ever found [19],[3]. Recent measurements of the acoustic correlates of speech rhythm are based on durational cues. Ramus, Nespor & Mehler [18] segment speech into vocalic and consonantal parts and calculate the proportion of the vocalic intervals of a sentence and the standard deviation of the consonantal intervals. Grabe & Low [7] measure the difference in duration between successive vowel durations and between successive consonantal intervals. Gibbon & Gut [6] calculate the ratio of adjacent syllable and vowel durations. These approaches have succeeded in describing rhythmic differences between languages [18],[7],[6] as well as between varieties of one language [14],[8]. It has been suggested that rhythmic differences between languages are correlated with other phonological properties of languages such as their syllable structure and phonological vowel length distinctions [3]. Whereas languages classified as stress-timed tend to have a variety of different syllable structures and phonological vowel length distinction, languages classified as syllable-timed usually have a majority of CV syllables and no vowel length contrast. In the area of tone, languages have been classified as tone languages, intonation languages and pitch accent languages [17]. In intonation languages, pitch carries semantic information but cannot be directly associated with lexical meaning. Conversely, the tones are used either on single words or groups of words of varying length and keep their relatively consistent meaning. Pitch accent languages use pitch for the differentiation of the meaning of various lexical items, but only limited to certain types of syllables or specific places in a word [17]. In tone languages, pitch is lexically significant, contrastive and relative. It is associated with tonebearing units such as the syllable or the morpheme. Tone is thus a feature of the lexicon. Some tone languages have tone that is sensitive to word structure and affixation and there seems to be a sliding scale to languages where tones have no lexically contrastive function anymore but use “tonal accents” instead [21]. 2. The Prosody of Nigerian English and other West African languages 2.1. Nigerian English prosody In Nigeria, an estimated 400 different local languages are spoken, with English being the medium of education, business, commerce and mass media. Nigerian English itself has distinct varieties, usually dependent on the speakers’ education and linguistic background [11],[22]. Standard Nigerian English is mainly spoken by University graduates and constitutes the socially most accepted variety. The prosody of Standard Nigerian English has been suggested to be syllable-timed rather than stress-timed [2],[22] although only very limited acoustic evidence is available [4],[22]. Nigerian English intonation differs systematically from British English intonation [12], and it has been suggested that it reflects the prosodic structure of the speaker’s native language in a way that stressed syllables are associated with a high tone and unstressed syllables with a low tone [23]. In fact, proposals have been made to treat Nigerian English as a tone language with tone on every syllable [8]. The first aim of this study is to find acoustic evidence for a classification of Nigerian English speech rhythm. It will be compared both with British English and three West African tone languages. Second, Nigerian English syllable structure will be compared with that of British English. Finally, the tonal structure of Nigerian English will be analysed. 2.2. Prosodic description of Anyi, Ega and Ibibio Anyi is spoken in the Eastern part of Ivory Coast and in Ghana and belongs to the Kwa languages. The following syllable structures occur in Anyi: V, CV, N, CVV, and CCV. Anyi has four phonological tones: Two level tones, H and L, and two contour tones, rising LH and falling HL. The appearance of a mid tone is due to the effect of tone sandhi rules. Ega is an isolate within a Kru speaking area of South Central Ivory Coast, with around 1000 full speakers. Although the language has been classified as Kwa, Ega has phonological features, such as the full implosive series, and morphological features, such as a complex nominal classification system, which distinguish it from the geographically nearest Kwa languages. Permissible syllable structures are V, CV, and CCV. The tone system of Ega has a three-way contrast: high (H), mid (M) and low (L). Ibibio has been classified as a Lower Cross language ((New) Benue-Congo) and is spoken in the south-eastern part of Nigeria. The Ibibio syllable structure is (V/N), CV, CVV, CVC, CVVC, and CCV. The V/N is the syllabic prefix, which may be either a vowel or a syllabic nasal consonant, usually homorganic to the following consonant. The tone system has two level pitches, High and Low, plus a contrastive downstepped High tone in addition to two contour tones, High-Low and Low-High. The contour tones are combinations of the level pitches.