Evaluation of acoustic characteristics of snoring sounds obtained during drug-induced sleep endoscopy.

Abstract

Snoring sounds are discussed to contain acoustic information about their geneses. Nocturnal snoring can easily be recorded acoustically but it is difficult to visually verify its genesis. Contrary, snoring patterns induced by drug-induced sleep endoscopy (DISE) can be visually differentiated. The aim of the study was to classify patterns of obstructions and vibration during DISE and to evaluate acoustic characteristics between these different patterns of snoring. DISE was performed in 41 male patients with sleep-disordered breathing. The recorded video sequences (n = 108) were classified visually at a mute mode in different patterns of snoring (velar, velar obstructive, tonsillar, post-apnoeic). The sound tracks of these subgroups were analysed and compared with regard to the parameters sound pressure level, loudness, sharpness, roughness, fluctuations strength and centre frequency. Obstructive snoring patterns revealed a higher loudness than non-obstructive patterns (>25sone). Velar snoring showed more roughness (>150cAsper) than tonsillar and post-apnoeic snoring and revealed the lowest centre frequency (<3000Hz) of all patterns. Tonsillar snoring presented the highest sharpness (>1.6acum) whereas post-apnoeic snoring revealed the largest fluctuation strength (>50cVacil). Different snoring patterns induced by DISE can be classified visually, and an approach to differentiate them acoustically by means of psychoacoustic analyses is demonstrated. On the basis of these results, nocturnal snoring might also be differentiated by psychoacoustic algorithms which could be implemented in acoustic polygraphic screening devices in the future.