title: Nocturnal sound analysis for the diagnosis of obstructive sleep apnea.
abstract: A novel method for screening obstructive sleep apnea syndrome (OSAs) based on nocturnal acoustic signal is proposed. Full-night audio signals from sixty subjects were segmented into snore, noise and silence events using semi-automatic algorithm based on Gaussian mixture models which achieves more than 90% (92%) sensitivity (specificity) and produces an average of 2,000 snores per subject. A classification into 3 groups is proposed for the diagnosis: comparison group - non-OSA subjects (apnea hypopnea index, AHI < 10), mild to moderate OSA (10 < AHI < 30) and severe OSA (AHI>30). A Bayes classifier was implemented, fed with five acoustic features, all correlated with the severity of the syndrome: (1) Inter Event Silence, which quantifies segments suspicious as apnea; (2) Mel Cepstability, measures the entire night stability of the spectrum, expressed using mel-frequency cepstrum; (3) Energy Running Variance, a criterion for the variation of the nocturnal acoustic pattern; (4) Apneic Phase Ratio, exploiting the finding that snores around apnea events expressing larger acoustic variation; and (5) Pitch Density. Correct classification of 92% for resubstitution method and 80% for 5-fold cross validation method was achieved. Moreover, in a case of two groups with a threshold of AHI=10, a sensitivity (specificity) of 96.5% (90.6%) and 87.5% (82.1%) for resubstitution and cross-validation respectively were obtained.
authors.affiliation: Department of Biomedical Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel. nirbeni@bgu.ac.il
authors.forename: Nir
authors.initials: N
authors.lastname: Ben-Israel
authors.forename: Ariel
authors.initials: A
authors.lastname: Tarasiuk
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Zigel
mesh_terms: D000162:Acoustics; D003624:Darkness; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012135:Respiratory Sounds / Q000175:diagnosis*; D020181:Sleep Apnea, Obstructive / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology; D012913:Snoring