Acoustic Analysis of the Swallowing Sound for Food Gels Relevant as Care Foods for Dysphagic Patients

Abstract

An acoustic analysis of sounds generated during the swallowing of gels with similar taste but different textures was conducted. These gels may have relevance as care foods for dysphagic patients. The profiles of the swallowing sounds of each subject were divided into three parts: the time required for the epiglottis to close (t₁), the time required for the bolus to flow (t₂), and the time required for the epiglottis to open (t₃). The time required for the bolus to flow through the pharynx, t₂, tended to decrease as the concentration of the gel increased, and approached that of yogurt, which is rarely aspirated. In addition, t₂ tended to decrease with an increase in the “hardness” obtained from TPA tests or with an apparent steady viscosity, μ, of the gel bolus. The time t₂ correlated well with the maximum velocity through the pharynx, V_max, which has been reported to correspond to the width of the velocity distribution of the bolus in the pharynx and to be a good predictor of aspiration risk. Therefore, the acoustic analysis of sounds could be a simple method for evaluating the velocity distribution of the bolus in the pharynx.