Development of the support system od dysphagic patients using automatic analyzing system of dysphagia

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This study was designed to establish the objective diagnosing system for dysphagia using the acoustic analyzing techniques of swallowing and expiratory sounds detected from the neck. New detecting instrument with active noise controller was developed. Acquisition system of acoustic signal of swallowing and expiratory sounds combined with the videofluorographic data was also developed. Analyzing system of the acoustic signals consists of the 250 Hz, 500 Hz, one-third octave, and 1 octave band analyses besides the automatically nomalyzing system of input level of the acoustic signals and the moduration transfer function.In this study, forty-three mixed pre-and post-surgical head and neck cancer patients with informed consent were examined. While patients swallowed 5 ml of barium (180% w/v), the expiratory sounds immediately after the swallows were detected using our method and fed to a VHS video recorder with videofluorographic (VF) images of these swallows and expiratory events.From the VF data, 92 exiratory sounds were produced after the swallow without aspiration or penetration and 118 exiratory sounds were produced after dysphagic swallows with aspiration or penetration.Acoustic signals of the expiratory sounds were analyzed by our computed acoustic analyzing system. Comparison of the diagnosis using the critical magnitude from 0 to 250 Hz band of expiratory sound siganals with the VF diagnosis showed significant agreement. Sensitivity was 83.2%, specificity 82.6% and percent agreement was 82.9%.