Nasal Airflow Patterns During the Velopharyngeal Closing Phase in Speech in Children With and Without Cleft Palate

Aerodynamic and Laryngeal Characteristics of Place-Dependent Voice Onset Time Differences

OBJECTIVE

To investigate aerodynamic and laryngeal factors associated with place-dependent voice onset time (VOT) differences.

METHODS

The speech materials were /p∧, t∧, k∧/, each produced 15 times by 10 adult English speakers in the carrier phrase "say __ again". The sound pressure level was targeted within a ±3 dB range. Intraoral air pressure (Po) was obtained using a buccal-sulcus approach. VOT, Po, maximum Po declination rate (MPDR), duration of the laryngeal devoicing gesture (LDG), occlusion duration, and the duration of the Po drop to baseline (atmosphere) to the onset of voicing (PDOV) were determined for each stop.

RESULTS

VOT was longer for the alveolar and velar stops compared to the bilabial stop. A constant LDG was observed for all stops regardless of place of articulation. Occlusion duration, however, was significantly shorter for the alveolar and velar stops compared to the bilabial stop. Aerodynamically, Po was greatest for the velar stop, intermediate for the alveolar stop, and smallest for the bilabial stop. MPDR index showed a slower rate of Po drop for the velar and alveolar stops compared with the bilabial stop. PDOV was found to be longer for /p/ than /t/ and /k/.

CONCLUSION

Findings provide empirical evidence for the inter-related roles of Po, rate of Po change, and laryngeal factors in place-dependent variations of VOT.

Instrumental assessment of velopharyngeal function and resonance: a review

The purpose of this literature review is to describe and discuss instrumental assessment techniques of the velopharyngeal function in order to diagnose velopharyngeal disorders and resonance characteristics. Both direct and indirect assessment techniques are addressed, in which successively nasopharyngoscopy, videofluoroscopy, magnetic resonance imaging (MRI), cephalometric radiographic analysis, computed tomography (CT), ultrasound, acoustic and aerodynamic measurements are considered. Despite the multiple instrumental assessments available to detect and define velopharyngeal dysfunction, the ideal technique is not yet accessible. Therefore, a combination of different quantitative parameters can possibly form a solution for a more reliable determination of resonance disorders. These multi-dimensional approaches will be described and discussed. The combination of quantitative measurement techniques and perceptual evaluation of nasality will probably remain necessary to provide sufficient information to make appropriate decisions concerning the diagnosis and treatment of resonance disorders.

LEARNING OUTCOMES

The reader will be able to describe and discuss currently available instrumental techniques to assess the velopharyngeal mechanism and its functioning in order to diagnose velopharyngeal disorders. Additionally, he will be able to explain the possible advantages of the combination of several types of complementary measurement techniques.

Characteristics of nasal resonance and perceptual rating in prelingual hearing impaired adults

Objectives

Resonance problems in hearing impaired (HI) individuals have been described as aspects of nasality. However, there are limitations in being able to explain the range of resonance problems. Therefore, this study suggests a perceptual rating that will effectively explain the characteristics of resonance problems in HI individuals.

Methods

Nasalance scores were obtained from 32 subjects in each of HI and normal hearing (NH) groups using a nasometer. The subjects were categorized into groups based on normal and abnormal nasalance ranges. The abnormal nasalance range group was further divided into hyper-, hypo-, and mixed-nasal groups. Nasalance scores were based the individuals performance in a series of passage and syllable tasks. The perceptual rating was evaluated using a newly introduced tool, 'vertical focus of resonance' (VFR), which focuses on the resonance energy in the frontal, throat, pharyngeal and nasal locations.

Results

The NH group demonstrated a significantly lower nasalance score in the oral coupling and passage tasks than the HI group. Based on the results of nasalance correlation analysis, the HI group showed highly significant correlations between syllable and passage tasks, as contrasted with the NH group. There were significant differences in VFR between the nasalance types in both the NH and the HI groups.

Conclusion

The HI hyper-nasal group showed tendencies of velopharyngeal opening, as opposed to the HI hypo-nasal group which showed tendencies of velopharyngeal closure. The HI mixed-nasal group showed inappropriate coordination of velopharyngeal function. In the HI group, the results of VFR showed that the air flow and the resonance energy were not released from the cavity of resonance. The suggested VFR tool explains the focusing characteristics of resonance energy within a continuation of speech sound regardless of the phonetic environment. Therefore, VFR may be a useful tool in explaining the deviant resonance patterns of HI individuals.