Planting the seed for sound change: Evidence from real-time MRI of velum kinematics in German

Velum movement signals generated from real-time magnetic resonance imaging videos of thirty-five German speakers were used to investigate the physiological conditions that might promote sound change involving the development of contrastive vowel nasality. The results suggest that, in comparison to when a nasal consonant precedes a voiced obstruent, the velum gesture associated with a nasal consonant preceding a voiceless obstruent undergoes gestural rescaling and temporal rephasing. This further suggests that the diachronic development of contrastive vowel nasality comprises two stages: the first stage involves gestural shortening and realignment, while the second stage involves a trading relationship between source and effect

Sensorimotor adaptation affects perceptual compensation for coarticulation

A given speech sound will be realized differently depending on the context in which it is produced. Listeners have been found to compensate perceptually for these coarticulatory effects, yet it is unclear to what extent this effect depends on actual production experience. In this study, whether changes in motor-to-sound mappings induced by adaptation to altered auditory feedback can affect perceptual compensation for coarticulation is investigated. Specifically, whether altering how the vowel [i] is produced can affect the categorization of a stimulus continuum between an alveolar and a palatal fricative whose interpretation is dependent on vocalic context is tested. It was found that participants could be sorted into three groups based on whether they tended to oppose the direction of the shifted auditory feedback, to follow it, or a mixture of the two, and that these articulatory responses, not the shifted feedback the participants heard, correlated with changes in perception. These results indicate that sensorimotor adaptation to altered feedback can affect the perception of unaltered yet coarticulatorily-dependent speech sounds, suggesting a modulatory role of sensorimotor experience on speech perceptio

Planting the seed of sound change: Evidence from real-time MRI of velum kinematics in German

Velum movement signals generated from real-time magnetic resonance imaging videos of thirty-five German speakers were used to investigate the physiological conditions that might pro-mote sound change involving the development of contrastive vowel nasality. The results suggest that, in comparison to when a nasal consonant precedes a voiced obstruent, the velum gesture as-sociated with a nasal consonant preceding a voiceless obstruent undergoes gestural rescaling and temporal rephasing. This further suggests that the diachronic development of contrastive vowel nasality comprises two stages: the first stage involves gestural shortening and realignment, while the second stage involves a trading relationship between source and effect

Hearing loss and the phonetic context effect

In order to gain a better understanding of how hearing loss influences speech perception, the influence of phonetic context on vowel identification was tested under simulated hearing loss conditions. Participants (n=17) were presented vowels along the /ε/ - /∧/ acoustic continuum in /bVb/ and /dVd/ contexts and instructed to indicate which vowel they heard in normal hearing, and mild and severe simulated hearing loss conditions. It was hypothesized that a phonetic context effect would be observed in the normal hearing condition, diminish in the mild hearing loss condition, and disappear in the severe hearing loss conditions. The percent of /ʌ/ responses were calculated and the categorical boundary was estimated for each context and compared for differences within and across conditions. Contrary to expectations, no context effect was found for the normal hearing and mild hearing loss conditions. However, an unexpected phonetic context effect was observed in the severe hearing loss condition. These results were difficult to interpret given the lack of a significant context effect in the normal hearing condition and suggested possible interference introduced by test or stimulus procedures. It should be noted, however, that 9 of the 17 participants did demonstrated the effect in the normal hearing condition, with many maintaining the effect across both hearing loss conditions

Temporal and Aerodynamic Aspects of Velopharyngeal Coarticulation: Effects of Age, Gender and Vowel Height

Previous studies on the normal patterns of velopharyngeal coarticulation did not provide a multidimensional description of the phenomenon. The primary objective of this study was to determine the effects of age, gender and vowel height on the temporal and aerodynamic aspects of nasal airflow segments related to velar coarticulation in the normal speech of children and adults. A secondary objective was to determine the within speaker variability of the segments. Speakers consisted of 20 children between the ages of 5 and 7 years, 20 children between 9 and 11 years and 20 adult speakers 18 years or older. Nasal and oral air flows were collected from the participants using partitioned oro-nasal masks during the production of vowel-nasal-vowel sequences (VNV) including /ini/ and /ana/ embedded in two carrier phrases. Temporal and aerodynamic measurements were obtained for anticipatory and carryover nasal airflow for (VNV) sequences including absolute (in seconds) and proportional duration, as well as the volume of nasal airflow (in milliliters) and the ratio of nasal to oral-plus-nasal airflow volume. A mixed design 3 x 2 x 2 x 2 ANOVA procedure was used to determine the effects of age group, gender, vowel height and production level (type of carrier phrase) on temporal and aerodynamic aspects of anticipatory and carryover nasal airflow. In addition, coefficient of variation (CV) was computed for both temporal and aerodynamic measures as an index to speaker\u27s variability. Group Analysis of Variance 3 x 2 ANOVA procedures were used to determine the effect of age group, gender, or both on within speaker variability for all temporal and aerodynamic measurements. The results of the analysis suggest a significant age effect (p \u3c .001) on both temporal aspects and on the absolute volume (ml) of anticipatory nasal airflow. Duration, absolutely (sec) and proportionally, and volume of nasal airflow (ml) decreased with increasing age. No significant age effect was found for carryover nasal airflow. However, a significant interaction between gender and vowel height was found. Female speakers produced longer duration than male speakers on high vowel contexts, and women produced greater volume of nasal airflow (ml) and greater ratio of nasal to oral-plus-nasal airflow. A significant production level effect was also found. Generally, all speakers exhibited reduced absolute (sec) and proportional duration as well as reduced nasal airflow volume (ml) when the carrier phrase contained \u27say\u27 preceding the VNV sequence compared to the one without \u27say\u27. Results of the CVs analysis showed main effect of age as well as age and gender interaction. Results indicate a reduction on variability with increasing age. Older boys and men exhibited greater variability than older girls and women particularly on high vowel context. Results of the study indicate that children and adults produce distinct patterns of temporal and aerodynamic aspect of anticipatory nasal airflow. Findings were consistent with previous studies that reduction in duration of speech segment and reduction in variability is a general pattern of speech development. It is also suggested that subtle gender differences in oral-pharyngeal anatomy as well as vowel-specific production patterns may explain the gender difference on high vowels. Results of the study were discussed in the light of Gestural Phonology view of speech development and velar movement. Clinical implications were suggested for the diagnosis and treatment of patients with velopharyngeal dysfunction