Origin of the sound components during pharyngeal swallowing in normal subjects

The aim of this study was to identify the origin of swallowing sound components by using modern techniques that can provide numeric, synchronized acoustic-radiologic data. We enrolled 15 volunteer subjects (10 men and 5 women, average age = 29.5 +/- 8 years) and used an X-ray camera connected to a video acquisition card to obtain synchronized acoustic-radiologic data (25 images/s). The subjects were asked to swallow 10 ml of a barium suspension. Each sound component was associated with a specific position of the bolus and the anatomic structure that was moving. The average duration of the pharyngeal sound was 690 +/- 162 ms. The durations of the laryngeal ascension sound and the laryngeal release sound were significantly different (72 +/- 38 ms and 106 +/- 47 ms, p < 0.001). The upper-sphincter opening sound was present in 100% of the recordings. Its duration was 185 +/- 103 ms and was significantly different from the two other sounds. The duration of the first interval was 108 +/- 44 ms and the duration of the second was 236 +/- 139 ms. This study allowed us to determine the origin of the three main sound components of the pharyngeal swallowing sound with respect to movements in anatomic structures and the different bolus positions.