Volume 117, Issue 1, January 2005
Index of content:
- SPEECH PRODUCTION 
Estimation of vocal dysperiodicities in disordered connected speech by means of distant-sample bidirectional linear predictive analysis117(2005); http://dx.doi.org/10.1121/1.1835511View Description Hide Description
The article presents an analysis of vocal dysperiodicities in connected speech produced by dysphonic speakers. The processing is based on a comparison of the present speech fragment with future and past fragments. The size of the dysperiodicity estimate is zero for periodic speech signals. A feeble increase of the vocal dysperiodicity is guaranteed to produce a feeble increase of the estimate. No spurious noise boosting occurs owing to cycle insertion and omission errors, or phonetic segment boundary artifacts. Additional objectives of the study have been investigating whether deviations from periodicity are larger or more commonplace in connected speech than in sustained vowels, and whether sentences that comprise frequent voice onsets and offsets are noisier than sentences that comprise few. The corpora contain sustained vowels as well as grammatically- and phonetically matched sentences. An acoustic marker that correlates with the perceived degree of hoarseness summarizes the size of the dysperiodicities. The marker values for sustained vowels have been highly correlated with those for connected speech, and the marker values for sentences that comprise few voiced/unvoiced transients have been highly correlated with the marker values for sentences that comprise many.
117(2005); http://dx.doi.org/10.1121/1.1835958View Description Hide Description
Speech development in children is predicated partly on the growth and anatomic restructuring of the vocal tract. This study examines the growth pattern of the various hard and soft tissue vocal tract structures as visualized by magnetic resonance imaging(MRI), and assesses their relational growth with vocal tract length (VTL). Measurements on lip thickness, hard- and soft-palate length, tongue length, naso-oro-pharyngeal length, mandibular length and depth, and distance of the hyoid bone and larynx from the posterior nasal spine were used from 63 pediatric cases (ages birth to 6 years and 9 months) and 12 adults. Results indicate (a) ongoing growth of all oral and pharyngeal vocal tract structures with no sexual dimorphism, and a period of accelerated growth between birth and 18 months; (b) vocal tract structure’s region (oral/anterior versus pharyngeal/posterior) and orientation (horizontal versus vertical) determine its growth pattern; and (c) the relational growth of the different structures with VTL changes with development—while the increase in VTL throughout development is predominantly due to growth of pharyngeal/posterior structures, VTL is also substantially affected by the growth of oral/anterior structures during the first 18 months of life. Findings provide normative data that can be used for modeling the development of the vocal tract.
The emergence of mature gestural patterns in the production of voiceless and voiced word-final stops117(2005); http://dx.doi.org/10.1121/1.1828474View Description Hide Description
The organization of gestures was examined in children’s and adults’ samples of consonant–vowel–stop words differing in stop voicing. Children (5 and 7 years old) and adults produced words from five voiceless/voiced pairs, five times each in isolation and in sentences. Acoustic measurements were made of vocalic duration, and of the first and second formants at syllable center and voicing offset. The predicted acoustic correlates of syllable-final voicing were observed across speakers: vocalic segments were shorter and first formants were higher in words with voiceless, rather than voiced, final stops. In addition, the second formant was found to differ depending on the voicing of the final stop for all speakers. It was concluded that by 5 years of age children produce words ending in stops with the same overall gestural organization as adults. However, some age-related differences were observed for jaw gestures, and variability for all measures was greater for children than for adults. These results suggest that children are still refining their organization of articulatory gestures past the age of 7 years. Finally, context effects (isolation or sentence) showed that the acoustic correlates of syllable-final voicing are attenuated when words are produced in sentences, rather than in isolation.