Lingual kinematic strategies used to increase speech rate: Comparison between younger and older adults JUSTINE V. GOOZE ´ E 1 , DAYNA K. STEPHENSON 1 , BRUCE E. MURDOCH 1 , ROSS E. DARNELL 1 , & LEONARD L. LAPOINTE 1,2 1 School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia, and 2 Department of Communication Disorders, Florida State University, Tallahassee, Florida, USA (Received 21 March 2003; accepted 23 March 2004) Abstract The primary objective of this study was to assess the lingual kinematic strategies used by younger and older adults to increase rate of speech. It was hypothesised that the strategies used by the older adults would differ from the young adults either as a direct result of, or in response to a need to compensate for, age-related changes in the tongue. Electromagnetic articulography was used to examine the tongue movements of eight young (M526.7 years) and eight older (M567.1 years) females during repetitions of /ta/ and /ka/ at a controlled moderate rate and then as fast as possible. The younger and older adults were found to significantly reduce consonant durations and increase syllable repetition rate by similar proportions. To achieve these reduced durations both groups appeared to use the same strategy, that of reducing the distances travelled by the tongue. Further comparisons at each rate, however, suggested a speed-accuracy trade-off and increased speech monitoring in the older adults. The results may assist in differentiating articulatory changes associated with normal aging from pathological changes found in disorders that affect the older population. Keywords: Aging, lingual dynamics, speech motor control, speech rate, electromagnetic articulography (EMA) Introduction Many physiological, anatomical and neurological changes occur in the human body as one ages. Common are reports of decreased skeletal muscle strength, muscle atrophy and increased muscle fatigability (Campbell, McComas, & Petito, 1973; Price, & Darvell, 1981; Wilder, 1984; Sonies, 1991; Crow, & Ship, 1996; Martini, 1998). Declines in sensory and motor nerve conduction velocity, motor unit loss, and a slowing of fine and gross motor movements (LaFratta, & Canestrari, 1966; Brown, 1972; Sonies, 1991) have also been observed, as have changes to the skeletal system, with bone loss and changes in bone composition (Sonies, 1991). Limited research has been carried out specifically to ascertain whether the same changes occur in the supralaryngeal structures (i.e., tongue, Correspondence: Justine Gooze ´e, Motor Speech Research Unit, Department of Speech Pathology and Audiology, The University of Queensland, Brisbane, Queensland 4072, Australia. Tel: 61 7 3365 3097. Fax: 61 7 3365 1877. E-mail: j.goozee@uq.edu.au Clinical Linguistics & Phonetics, June 2005; 19(4): 319–334 ISSN 0269-9206 print/ISSN 1464-5076 online # 2005 Taylor & Francis Ltd DOI: 10.1080/02699200420002268862