Quantification of rhythm problems in disordered speech: a re-evaluation

Disordered speech can present with rhythmic problems, impacting on an individual''s ability to communicate. Effective treatment relies on the availability of sensitive methods to characterize the problem. Rhythm metrics based on segmental durations originally designed for cross-linguistic research have the potential to provide such information. However, these measures may be associated with problems that impact on their clinical usefulness. This paper aims to address the perceptual validity of cross-linguistic metrics as indicators of rhythmic disorder. Speakers with dysarthria and matched healthy participants performed a range of tasks, including syllable and sentence repetition and a spontaneous monologue. A range of rhythm metrics as well as clinical measures were applied. Results showed that none of the metrics could differentiate disordered from healthy speakers, despite clear perceptual differences, suggesting that factors beyond segment duration impacted on rhythm perception. The investigation also highlighted a number of areas where caution needs to be exercised in the application of rhythm metrics to disordered speech. The paper concludes that the underlying speech impairment leading to the perceptual and acoustic characterization of rhythmic problems needs to be established through detailed analysis of speech characteristics in order to construct effective treatment plans for individuals with speech disorders.     

Determining replication for discrimination among microbial communities in environmental samples using community-level physiological profiles

A statistical approach was employed to assess microbial community variability within a single 4-l water sample and among 10 independent 4-l water samples from a single location using community-level physiological profiles. Power calculations demonstrated that duplicate analyses could distinguish between two different locations at two times during the year. Variability associated with replicates from a single container or from different containers was nearly the same for the two sites examined. Duplicate assays (one from each of two independent samples) were sufficient to resolve the between-site differences at alpha=0.05 with power exceeding 0.95 at both times of the year. Similar methods are recommended to determine the appropriate number of replicates for environments of interest.