[Study of deglutition using various sound signals]

In man quantitative information on deglutition may be obtained with the aid of various sounds recorded by way of microphone and magnetic tapes. The different tapes, microphonic, dynamic and piezoelectric, can be compared through the use of a Doppler signal in high middle position, thus showing the backward movements of the mylohyoïdeus. The sound of the deglutition consists of 1 to 3 peaks of great amplitude: 350 +/- 180 microV or 14 +/- 3.3 mV according to the type of microphone used (the piezo gives the greatest amplitude, specially in low frequency range); duration for the main phoneburst: 48 +/- 24 ms with a prolongation with the smaller noises: so total duration amounts to 400 ms. Each sound impulsion repeated in 10 Hz range includes frequency up to 6 KHz. The direct recording on a polygraph falls into 10-60 range; upper frequencies may be eliminated by filtering. In front, the inspiratory relative time increases of 57 +/- 12% without deglutition whereas it reaches 62 +/- 16% with deglutition. In clinical situation, a magnetic tape recorder can be used. The main components in normal situation of deglutition of saliva, water or yogurt show a frequent variability. Nevertheless, a certain number of recurring impulsions can be defined according to the type of deglutition, thus further defining several basic types of deglutition. Amplitude and duration deglutition type 1 (= one impulsion) was observed in young subjects for saliva and yogurt; deglutition type 2-3 (greater than or equal to 200 ms) more frequently for water and also in oldest subjects, whatever the mode of deglutition. In some pathological situations, a significant increase of amplitude and duration was observed. Technical conditions are discussed for application in clinical situations and their control in laboratory.