Variability of snore parameters in time and frequency domains in snoring subjects with and without Obstructive Sleep Apnea.

Several studies have shown differences in spectral parameters between simple snorers and patients with Obstructive Sleep Apnea Syndrome (OSAS). Most of them analyzed a reduced number of snores and/or only post-apneic snores were selected in OSAS patients. Previous findings suggest that snore parameters have a greater variability as the severity of OSAS increases. In this work we propose to analyze the snoring variability through the magnitude of the first difference of snore parameters. The technique is applied to long time sound recordings from 9 simple snorers (15795 snores) and 15 OSAS patients (19263 snores). The snores are characterized by their sound intensity an by a set of spectral parameters The variability of snore parameters is well correlated to OSAS severity (r>0.7) and is significantly greater in OSAS patients than in simple snorers (p<0.005). The results are similar when post-apneic snores are excluded from the analysis. Snoring subjects are classified with a logistic regression model, which is validated with the live-one-out method. The model is adjusted to correctly classify 100% of OSAS patients for screening purposes previously to enroll for a whole polysomnographic study.