Correspondence: Inger Lundeborg, Department of Clinical and Experimental Medicine, Division of Speech and Language Pathology, Linköping University, S-501 85 Linköping, Sweden. E-mail: Inger.lundeborghammarstrom@liu.se (Received 23 October 2012; accepted 7 June 2014) ORIGINAL ARTICLE Voice onset time in Swedish children with phonological impairment INGER LUNDEBORG 1 , ELIN NORDIN 1 , MARIE ZEIPEL-STJERNA 1 & ANITA MCALLISTER 1,2 1 Department of Clinical and Experimental Medicine, Division of Speech and Language Pathology, Linköping University, Sweden, and 2 Department of Clinical Science, Intervention and Technology, Karolinska Institute, Stockholm, Sweden Abstract Mastering spatial and temporal co-ordination in speech production is a challenge for children. Voice onset time (VOT) reflects timing in speech. The objective was to study VOT in Swedish children with a diagnosed phonological impairment and compare results with normative data. Thus 38 children, aged 4–11 years, in three age-groups were audio-recorded when producing minimal pairs with the plosives /p b t d k g/. Waveforms and spectrograms were analysed. Results show that children with phonological impairment produced plosives with deviant VOT values and greater variability compared to normative data. No developmental trend was seen with increasing age. Also, no relationship was found between VOT values and degree of impairment measured by percentage phonemes correct. Furthermore no relation was found between number of errors on auditory discrimination of nine minimal pairs with the different plosives and number of deviant VOT. Findings were interpreted as displaying motor co-ordination difficulties. Key words: Child, speech sound disorders, voice onset time Introduction Human speech is a complex motor behaviour, and the developing child needs many years to establish adult mastery of the phonemic contrasts in a given language. However, without a communicative intent intermediated by language symbols, speech has no meaning. The process of phonological acquisition in children has been described as a process of organizing and learning the mappings between the auditory speech input and the gestural control of speech output (1). Phonological ability also improves through increased capacity to produce adult sounds and com- bine them into more complex phonological struc- tures (2). Motor speech control has traditionally been regarded as separated from phonological oper- ations, but in, for example, gestural phonology issues in phonology and articulation are addressed simul- taneously (3). A relationship between oral motor control and speech and language development has been reported by several authors (4–6). However, to which extent oral motor skills influence language development requires further research. Children with speech problems form a large but heterogeneous group, and a multitude of diagnostic terms has been used to describe speech disorders without obvious causation. One of the ongoing debates within the study of developmental speech and language disorders concerns whether children’s impaired speech is caused by incomplete linguistic knowledge, processing deficits, or limited motor speech control (4,7). The multidimensional require- ments in speech production continue to elude researchers and present problems for clinicians. Regarding the aspect of motor control different degrees of motor co-ordination and control are required for production of different speech sounds. Plosives are among those which demand close co-ordination of breathing and the laryngeal and the supra-laryngeal structures. In clinical practice auditory-perceptual evaluations form the basis for assessments of the voicing aspect of plosives. Logopedics Phoniatrics Vocology, 2014; Early Online: 1–7 ISSN 1401-5439 print/ISSN 1651-2022 online © 2014 Informa UK, Ltd. DOI: 10.3109/14015439.2014.934276 Logoped Phoniatr Vocol Downloaded from informahealthcare.com by Karolinska Institutet University Library on 07/27/14 For personal use only.