Establishing Norm of Connected Speech Measures for Descriptive Discourses in Cantonese-Speaking Adults

Normative reference of the connected speech measures (both micro-structural and macro-structural) for descriptive discourse is fundamental to systematic discourse analysis because it provides an anchor for comparison. This study aims to establish a comprehensive normative reference for connected speech measures in Cantonese by analysing a wide array of micro- and macro-structural measures, investigating the impact of age and education on these measures, and examining potential performance differences across various genres of descriptive discourse tasks.

The sample included 149 healthy Cantonese-speaking adults who were categorized into three age groups (young, middle-aged, and old) and two education levels (high and low). Speech samples were collected, transcribed, and analysed based on five descriptive discourse tasks in the Cantonese AphasiaBank, including two single-picture descriptions (Flood and Cat rescue), two sequential picture descriptions (Broken window and Refuse umbrella), and one procedural description (Egg and ham sandwich).

Normative reference of multiple connected speech measures (such as type, token, noun-verb ratio, Information Content Units [ICU] and Main Concepts [MC]) and lists of standard scoring criteria for the ICU and MC for the five tasks were presented. For age effect, statistical analysis revealed that the old group demonstrated less informativeness and fluency than younger groups across genres. Specifically in procedural description, the middle-aged group showed superior verbal productivity compared to the other groups and informativeness compared to the old group. For education effect, the high-education group outperformed the low-education group in verbal productivity and informativeness across genres. Age-education interaction was found in syntactic complexity measures across genres.

These findings contribute to building a comprehensive normative reference for the evaluation of connected speech, providing a complementary tool for systematic and objective assessment.

What is already known on this subject In the clinical context of assessment, discourse analysis is a crucial method for assessing language ability in individuals with acquired language impairments such as aphasia. Normative reference of the above-mentioned connected speech measures (both micro-structural and macro-structural) is fundamental to systematic discourse analysis because it provides an anchor for comparison. Apart from discourse tasks from traditional aphasia assessment batteries, a large set of US English norms have also been established for discourse tasks included in the aphasia language databases of AphasiaBank. What this study adds This is one of the very few reports in Cantonese that established a comprehensive and large-scale normative reference for connected speech measures based on spontaneous oral discourse production from a sizeable group of native Cantonese speakers. Normative reference of an extensive array of connected speech measures, which includes multiple micro-structural (linguistically-based) and macro-structural (content-based) measures is provided. What are the clinical implications of this study? Establishment of this linguistically and culturally specific normative reference enables more systematic and objective assessment of connected speech production in diseased populations, such as aphasia. Uncovering the effects of age and educational is crucial for theoretical inference of the impact of ageing and education level on language proficiency, as neglecting these effects can lead to biased comparisons when applying the norm to make clinical inferences.