Use of reaction time in the temporal analysis of normal swallowing.

This study was performed to establish the swallowing trigger by using the reaction time from an auditory stimulus. With this stable temporal starting point, we described the chronology of the different acoustic, electrophysiologic, and respiratory events that occurred during swallowing in a population of normal adults. We studied the swallowing reaction time (SRT) in 18 subjects aged 23 to 73 years by using acoustic, electroglottographic (EGG), and aerodynamic recordings. The chronology (the beginning of EGG activity, apnea, and respiratory sound and release) was identified in 91% of the recordings. The average SRT was 264 ms and the average swallowing duration was 977 ms, without any significant difference with respect to gender. The swallowing sound produced during apnea was composed of either two or three components. The reaction time procedure also demonstrated that the first sound component was unstable. By using this procedure for studying swallowing, we were able to stabilize the chronology of the different events, improve the subjects' attention, and establish a fixed benchmark for performing temporal measurements.