Phonetic and Phonological Features of Typical and Atypical Speech: Insights from Bangla Language

Abstract

The present research provides statistical analyses of the phonetic and phonological features for Bangla typical and atypical speech. It identifies and categorizes the distinctive sound features and then devises necessary articulatory and acoustic tools to analyze the data for Bangla typical and typical speech. The study identifies presences and absences of sounds, along with alterations, and also newly identifiable features following the distinctive feature matrix theory. It also looks into the articulatory and acoustic properties, theories, mechanisms, characteristics and transcription of typical and atypical speech, a synopsis of the standard variety, dialectical variations and individual differences, cross-linguistic perspective on Bangla phonetics and integrating features, existing IPA, extIPA chart along with historical contexts of Bangla typical and atypical speech. Later on, it suggests revisions of principles which were used in transcribing atypical speech of Bangla language. In order to collect data, two Task-based Phonological Tests has been devised: (a) picture naming and (b) word naming. All atypical participants are diagnosed aphasic patients, primarily from Bangladesh Medical University (formerly BSMMU) and Metropolitan Medical Centre Ltd. The patients have suffered from Broca’s Aphasia after cerebrovascular accident (CVA) with impressions of intracerebral haematoma in the cerebral hemisphere and are at the early stage of treatment and speech therapy, i.e., within 6 months to a year. The research was concluded by listing the most common features of atypical speech, along with affected organs. It identifies pre-palatalization /ʲ◌/, nasal release /◌ⁿ/, lip compression /◌͍/, fricative release /◌ˣ/ (and /◌ˢ/, /◌ᶠ/ as systematic release markers), strong articulation /◌͈/, weak articulation /◌͉/, inconsistent /O/, unaspirated /◌˭/ (often unmarked), unintelligible speech /◌/. pre-aspirated /ʰ◌/, partial devoicing /₍◌̥₎/, sliding articulation /◌͢◌/, double articulation /◌͡ ◌/, aspirated fricative /◌ʰˢ/ as newly identifiable symbols for atypical speech representation for Aphasic patients who speak Bangla as L1. Unintelligible speech /◌/ can also be suggested as new. Low tone (˨), Extra-Low Tone (˩), Weak Articulation (◌͉), Retracted Tongue-Root v Position (◌̙) are prominent in most utterances. In a few cases, Post-Alveolar Clicks (◌ǃ) and Palatal Clicks (◌ǂ) were observed. Various places of articulation include: /◌͉/ – linguolabial, /◌ʷ/ – labialized, /◌̪/ – dental, bidental /◌ʭ/, /◌ˠ/ – velarized, pre-palatalized /ʲ◌/, and manners of articulation include: /◌ˢ/ – sibilant, /◌̃/ – nasalized, nasal release /◌ⁿ/, /◌ʳ/ – trill/tap. As for organs, soft palate/Velum , back and the root of the tongue are mostly affected. Also, it finds that the highest form of atypical speech occurs due to velarization and nasal release/nasalization which can be considered under distortion. Other significant errors happen due to retracted tongue-root position, creaky-voice, rising-falling tone, nasal release/nasalization and no audible release. Creaky-voice and rising-falling tone can be considered as suprasegmental features, and retracted tongue-root position can cause phonological or acoustic errors which all leads to distortion. No audible release, on the other hand, can lead to omission. In addition, the research shows that in dialect variation, F1-F2 relationships shift in predictable and consistent ways. The research presents all the data in percentages. To summarize, the research aims to revisit and catalogue the articulatory and acoustic features of Bangla typical speech, devise necessary articulatory and acoustic tools to collect Bangla typical and atypical speech, and propose amendments to the existing extIPA for disordered speech in the context of Bangla atypical speech. Thus it provides a systemic analysis on speech production of atypical speech and bridges the gaps between the theoretical and practical applications. Hence, it provides culturally and linguistically appropriate research-based resources (e.g., pictographic tools, communication-ready materials) for speech-language pathologists (SLPs) dedicated towards Aphasic patients who speaks Bangla as their L1. In future, this shall add to the direct service to the patients and their families for assessment, therapy, support and build collaboration and capacity building among the professionals (speech-language therapists, health workers) through training, etc. Following this model, other disorders can also be explored.