Effects of age, gender, bolus volume and viscosity on acoustic signals of normal swallowing

Objective: The purpose of this investigation was to determine the effects of rage, gender, bolus volume and bolus viscosity on the acoustic signals of normal swallows. Materials and Methods: Healthy volunteers (n=146) ranging from 3 to 85 years of age participated in the investigation. Subjects were grouped by age: 3-5, 18-25 and 70-85 years of age. Subjects performed a series of swallows that were randomized according to volume and viscosity. A total of 3056 swallows were analyzed. Four temporal events were compared; acoustic onset, acoustic peak, acoustic spike associated with the small non-inspiratory flow, and acoustic offset. Results: In the youngest group, a significant effect was found for volume, viscosity and gender for the time of acoustic onset (p<0.01). In the oldest age group, the variability for acoustic onset was much higher than in the other age groups (p<0.01). The oldest group had a substantially longer acoustic duration, especially for men (p<0.01). Additionally, a significant effect for viscosity and volume for the time of acoustic offset was found in the oldest age group (p<0.01). Conclusion: During normal swallowing, it was determined the effects of age, gender, holus volume, and bolus viscosity on the acoustic signals of normal swallow.