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Normal Swallowing Acoustics Across Age, Gender, Bolus Viscosity, and Bolus Volume

Cervical auscultation has been proposed as an augmentative procedure for the subjective clinical swallowing examination due to the tangible differences between normal and dysphagic swallowing sounds. However, the research is incomplete regarding cervical auscultation and swallowing acoustics in that the differences between the sounds of normal versus dysphagic swallowing have yet to be fully understood or quantified. The swallows of 96 reportedly healthy adults, balanced for gender and divided into younger, middle, and older age groups, were audio-recorded while ingesting several boluses of varying viscosity and volume. The audio signals were then analyzed to determine their temporal and acoustic characteristics. Results indicated increasing pharyngeal swallowing duration with increasing age, bolus viscosity, and bolus volume. In addition, an increased duration to peak intensity with increasing age was found in one of our two analyses, as well as with some of the more viscous versus less viscous boluses. Men and older persons produced higher peak intensities and peak frequencies than women and younger persons. Thin liquids were produced with more intensity than honey or more viscous boluses, and with greater frequency than mechanical soft solids. Larger volumes resulted in greater peak frequency values. Some of the acoustic measurements appear to be more useful than others, including the duration of the acoustic swallowing signal and the within-subjects peak intensity variable. We noted that differences in swallowing acoustics were more related to changes in viscosity rather than volume. Finally, within-participant observations were more useful than between-participant observations.

from Dysphagia

Anthropometric and Demographic Correlates of Dual-Axis Swallowing Accelerometry Signal Characteristics: A Canonical Correlation Analysis

Abstract Swallowing accelerometry has been proposed as a potential minimally invasive tool for collecting assessment information about swallowing. The first step toward using sounds and signals for dysphagia detection involves characterizing the healthy swallow. The purpose of this article is to explore systematic variations in swallowing accelerometry signals that can be attributed to demographic factors (such as participant gender and age) and anthropometric factors (such as weight and height). Data from 50 healthy participants (25 women and 25 men), ranging in age from 18 to 80 years and with approximately equal distribution across four age groups (18-35, 36-50, 51-65, 66 and older) were analyzed. Anthropometric and demographic variables of interest included participant age, gender, weight, height, body fat percent, neck circumference, and mandibular length. Dual-axis (superior-inferior and anterior-posterior) swallowing accelerometry signals were obtained for five saliva and five water swallows per participant. Several swallowing signal characteristics were derived for each swallowing task, including variance, amplitude distribution skewness, amplitude distribution kurtosis, signal memory, total signal energy, peak energy scale, and peak amplitude. Canonical correlation analysis was performed between the anthropometric/demographic variables and swallowing signal characteristics. No significant linear relationships were identified for saliva swallows or for superior-inferior axis accelerometry signals on water swallows. In the anterior-posterior axis, signal amplitude distribution kurtosis and signal memory were significantly correlated with age (r = 0.52, P = 0.047). These findings suggest that swallowing accelerometry signals may have task-specific associations with demographic (but not anthropometric) factors. Given the limited sample size, our results should be interpreted with caution and replication studies with larger sample sizes are warranted.

from Dysphagia

Variability of Swallow-associated Sounds in Adults and Infants

from Dysphagia

Abstract We previously used cervical auscultation (CA) to describe the stability of swallow-associated sounds of infant feeding. To date, no similar studies have been performed in adults. The objectives of this study were to identify the initial discrete sounds (IDS) of adult swallows and compare the stability of IDS signals in infants to that of adults. We performed CA with a microphone and accelerometer fixed simultaneously to the neck of 20 healthy adults. Each participant consumed a liquid, puree, and solid. The microphone and accelerometer collected signals of similar duration. The variance index (VI), an assessment of the stability of the IDS, was compared in adults and a group of low-risk preterm infants. The VI of adults swallowing liquid (29.1 [24.1, 36.6] {25%, 75%}) did not differ from that of preterm infants older than 36 weeks PMA (36.3 [33.4, 41.9]), but was lower than the VI of infants younger than 36 weeks PMA (49.0 [46.4, 51.1]; p < 0.05). This is the first real-time comparison of microphones and accelerometers for CA. The stability of IDS of low-risk preterm infants approaches that of normal adults as the infants age. Because successful feeding in infants is often used as a surrogate for normal development, the stability of swallow-associated sounds deserves more investigation as a potential marker for neurologic well-being.