Background: A previous study has pointed out the lack of diadochokinesis (DDK) normative data for the older population and, thus, provided norms based on speakers of Australian English. As it has been shown that speakers of different accents of a language could have different articulation and speaking rates, it makes sense to hypothesise that speakers of different accents will show different DDK rates as well. This study aims to establish norms of DDK rates for older Irish-English speakers as the data is currently not available, and to compare two methods of measuring DDK rates.
Methods: Eighty-eight healthy speakers of Irish English (22 men and 22 women of age 65-74 years and the same for age 75-86) are recruited. The speakers are instructed to repeat each of ‘pa’, ‘ta, ‘ka’, ‘pata’, ‘kata’, ‘plukrutu’, ‘pataka’ and ‘fasaha’ three times for as fast and accurate as they can. The productions are recorded using a digital audio recorder. The DDK rate of each production are measured using an acoustic analysis software using two methods: (1) the first 9 syllable or syllable sequence produced; and (2) all syllables within 5 seconds.
Results: Data collection is under way. Mean, standard deviation and range of DDK rate for each syllable or syllable sequence will be obtained for each speaker group. Two-way between-groups ANOVA will be used to test whether the DDK rate differ between men and women across the two age groups for each syllable or syllable sequence. Intra-class correlation coefficient will be used to assess intra- and inter-rater reliability.
Conclusion: Based on previous findings, it is hypothesised that (1) the DDK rates of the male speakers will be higher than that of the female speakers; and (2) the variability of DDK rates will be higher for the speakers of 75-86 years compared to that of the speakers of 65-74 years.