Phonetic complexity and stuttering in Spanish.

The current study investigated whether phonetic complexity affected stuttering rate for Spanish speakers. The speakers were assigned to three age groups (6-11, 12-17 and 18-years plus) that were similar to those used in an earlier study on English. The analysis was performed using Jakielski's Index of Phonetic Complexity (IPC) scheme in which each word is given an IPC score based on the number of complex attributes it includes for each of eight factors. Stuttering on function words for Spanish did not correlate with IPC score for any age group. This mirrors the finding for English that stuttering on these words is not affected by phonetic complexity. The IPC scores of content words correlated positively with stuttering rate for 6-11-year-old and adult speakers. Comparison was made between the languages to establish whether or not experience with the factors determines the problem they pose for speakers (revealed by differences in stuttering rate). Evidence was obtained that four factors found to be important determinants of stuttering on content words in English for speakers aged 12 and above, also affected Spanish speakers. This occurred despite large differences in frequency of usage of these factors. It is concluded that phonetic factors affect stuttering rate irrespective of a speaker's experience with that factor.

Phonetic difficulty and stuttering in English.

Previous work has shown that phonetic difficulty affects older, but not younger, speakers who stutter and that older speakers experience more difficulty on content words than function words. The relationship between stuttering rate and a recently-developed index of phonetic complexity (IPC, Jakielski) was examined in this study separately for function and content words for speakers in 6-11, 11 plus-18 and 18 plus age groups. The hypothesis that stuttering rate on the content words of older speakers, but not younger speakers, would be related to the IPC score was supported. It is argued that the similarity between results using the IPC scores with a previous analysis that looked at late emerging consonants, consonant strings and multiple syllables (also conducted on function and content words separately), validates the former instrument. In further analyses, the factors that are most likely to lead to stuttering in English and their order of importance were established. The order found was consonant by manner, consonant by place, word length and contiguous consonant clusters. As the effects of phonetic difficulty are evident in teenage and adulthood, at least some of the factors may have an acquired influence on stuttering (rather than an innate universal basis, as the theory behind Jakielski's work suggests). This may be established in future work by doing cross-linguistic comparisons to see which factors operate universally. Disfluency on function words in early childhood appears to be responsive to factors other than phonetic complexity.

Stuttering on function and content words across age groups of German speakers who stutter.

Recent research into stuttering in English has shown that function word disfluency decreases with age whereas content words disfluency increases. Also function words that precede a content word are significantly more likely to be stuttered than those that follow content words (Au-Yeung, Howell and Pilgrim, 1998; Howell, Au-Yeung and Sackin, 1999). These studies have used the concept of the phonological word as a means of investigating these phenomena. Phonological words help to determine the position of function words relative to content words and to establish the origin of the patterns of disfluency with respect to these two word classes. The current investigation analysed German speech for similar patterns. German contains many long compound nouns; on this basis, German content words are more complex than English ones. Thus, the patterns of disfluency within phonological words may differ between German and English. Results indicated three main findings. Function words that occupy an early position in a PW have higher rates of disfluency than those that occur later in a PW, this being most apparent for the youngest speakers. Second, function words that precede the content word in a PW have higher rates of disfluency than those that follow the content word. Third, young speakers exhibit high rates of disfluency on function words, but this drops off with age and, correspondingly, disfluency rate on content words increases. The patterns within phonological words may be general to German and English and can be accounted for by the EXPLAN model, assuming lexical class operates equivalently across these languages or that lexical categories contain some common characteristic that is associated with fluency across the languages.

Exchange of disfluency with age from function words to content words in spanish speakers who stutter.

The main purpose of the present study was to examine whether the developmental change in loci of disfluency from mainly function words to mainly content words, observed for English speakers who stutter (P. Howell, J. Au-Yeung, & S. Sackin, 1999), also occurs for comparable Spanish speakers who stutter. The participants were divided into 5 age groups. There were 7 participants in Group 1, from 3 to 5 years old; 11 in Group 2, from 6 to 9 years old; 10 in Group 3, from 10 to 11 years old; 9 in Group 4, from 12 to 16 years old; and 9 in Group 5, from 20 to 68 years old. Across all groups, 36 of the 46 participants were male. The study method involved segmenting speech into phonological words (PWs) that consist of an obligatory content word with optional function words that precede and follow it. The initial function words in the PWs were examined to establish whether they have a higher disfluency rate than the final ones (J. Au-Yeung, P. Howell, & L. Pilgrim, 1998). Disfluency on function words in a PW was higher when the word occurred before a content word rather than after a content word for all age groups. Disfluencies on function and content words were then examined to determine whether they change over age groups in the same way as for English speakers who stutter (Howell et al., 1999). The rate of disfluency on function words was higher than that on content words, particularly in the youngest speakers. Function word disfluency rate dropped off and content word disfluency rate increased across age groups. These patterns are similar to those reported for English. Possible explanations for these similarities across the two languages are discussed.

Syntactic development in fluent children, children who stutter, and children who have English as an additional language.

Children aged between two and 10 years were assessed on a new reception of syntax test (ROST). Validations of the test are reported for monolingual fluent control children under five (by examining the relationship with mean length of utterance and the Oxford Communication Development Inventory) and for over fives (relationship with a new judgement of grammaticality test using syntactic categories common to the two tests). Performance of these children was compared with performance of children who stutter and children with English as an additional language. In this study, the test was divided into under-five and over-five forms. Any young child progressing to the over-five syntactic categories, or any older child doing the under-five syntactic categories was dropped from the analysis. ROST scores prepared according to this scheme led to no differences between the control and either of the subject groups tested. However, compared to controls, the children with English as an additional language (but not children who stutter) had a significantly higher proportion of children above five who did the under-five categories (and were, therefore, excluded from the analyses). The higher proportion of children who did the under-five syntactic categories in the English as an additional language group indicates that group scores would have been lower if their syntax results had been included in the analysis. Further analyses provided some evidence that two groups with English as an additional language (Turkish and Cantonese speakers) did not perform any better on selected syntactic categories in their native language compared with their performance in English.

Non-word reading, lexical retrieval and stuttering: comments on Packman, Onslow, Coombes and Goodwin (2001).

A recent study by Packman, Onslow, Coombes and Goodwin (2001) employed a non-word-reading paradigm to test the contribution of the lexical retrieval process to stuttering. They consider that, with this material, the lexical retrieval process could not contribute to stuttering and that either anxiety and/or the motor demand of reading are the governing factors. This paper will discuss possible processes underlying non-word reading and it argues that the conclusion arrived at by Packman et al. does not stand up to close scrutiny. In their introduction, the authors acknowledge that the lexicalization process involves retrieval and encoding of words. In a non-word-reading task, the word retrieval component is eliminated. The possibility that the encoding component of the lexicalization process leads to stuttering is, however, completely ignored by the authors when they attribute stuttering to motor demands. As theories put forward by Postma and Kolk (the Covert Repair Hypothesis, 1993) and Howell and Au-Yeung (the EXPLAN theory, 2002) argue heavily for the role of the phonological encoding processes in stuttering, Packman et al.'s work does not evaluate such theories. Theoretical issues aside, Packman et al.'s arguments about reading rate and stuttering rate based on reading time is also questionable.

INTERNAL STRUCTURE OF CONTENT WORDS LEADING TO LIFESPAN DIFFERENCES IN PHONOLOGICAL DIFFICULTY IN STUTTERING.

This study investigated whether frequency of stuttering was affected by factors that specify the phonological difficulty of a sound and whether and how any influences vary across age groups. Analyses were performed separately on content words and function words. The phonological factors examined were: a) Whether the word contained a late emerging consonant (LEC); and b) Whether the word contained a consonant string (CS). Analyses showed that these factors occurred at different rates across the age groups used (children under 12, teenagers between 12 and 18, and adults). A more detailed breakdown was also reported of frequency of usage of LEC and CS over age groups depending on whether and where these factors occurred in the content words; all nine combinations of no LEC, word-initial LEC, non-initial LEC with no CS, word-initial CS, and non-initial CS were examined. Usage of certain of these nine categories varied over age groups. Friedman statistic on the ratio of stuttering (proportion of stuttered words in a particular word class divided by the proportion of words in that particular word class) showed that the frequency of stuttering remained high for adult speakers when CS and LEC both occurred in a word and when they appeared in word-initial position. These findings support a recently proposed theory that accounts for life-span changes in stuttering.