Oral diadochokinetic rates across languages: Multilingual speakers comparison.

Background: It is unclear whether oral diadochokinetic rate (oral-DDK) performance is affected by different languages within a multilingual country.

Aims: This study investigated the effects of age, sex, and stimulus type (real word in L1, L2 vs. non-word) on oral-DDK rates among healthy Malaysian-Malay speakers in order to establish language- and age-sensitive norms. The second aim was to compared the nonword 'pataka' oral-DDK rates produced by Malaysian-Malay speakers on currently available normative data for Hebrew speakers and Malaysian-Mandarin speakers.

Methods & Procedures: Oral-DDK performance of 90 participants (aged 20-77 years) using nonword ('pataka'), Malay real word ('patahkan'), and English real word ('buttercake') was audio recorded. The number of syllables produced in 8 seconds was calculated. Mixed analysis of variance (ANOVA) was conducted to examine the effects of stimulus type (nonword, Malay, and English real word), sex (male, female), age (younger, 20-40 years; middle, 41-60 years; older, ≥61 years), and their interactions on the oral-DDK rate. Data obtained were also compared with the raw data of Malaysian-Mandarin and Hebrew speakers from the previous studies.

Outcomes & Results: A normative oral-DDK rate has been established for healthy Malaysian-Malay speakers. The oral-DDK rate was significantly affected by stimuli (p < 0.001). Malay real word showed the slowest rate, whereas there was no significant difference between English real word and nonword. The oral-DDK rate for Malay speakers was significantly higher than Mandarin and Hebrew speakers across stimuli (all p < 0.01). Interestingly, oral-DDK rates were not affected by age group for Malay speakers.

Conclusions & Implications: Stimuli type and language affect the oral-DDK rate, indicating that speech-language therapists should consider using language-specific norms when assessing multilingual speakers.

What This Paper Adds: What is already known on the subject Age, sex, and language are factors that need to be considered when developing oral-DDK normative protocol. It is unclear whether oral-DDK performance is affected by different languages within a multilingual country. What this paper adds to existing knowledge No ageing effect across real word versus nonword on oral-DDK performance was observed among Malaysian-Malay speakers, contrasting with current available literature that speech movements slow down as we age. Additionally, Malaysian-Malay speakers have faster oral-DDK rates than Malaysian-Mandarin and Hebrew speakers across all stimuli. What are the potential or actual clinical implications of this work? Establishing normative data of different languages will enable speech-language therapists to select the appropriate reference dataset based on the language mastery of these multilingual speakers.