title: Investigation of sequential properties of snoring episodes for obstructive sleep apnoea identification.
abstract: In this paper, 'snore regularity' is studied in terms of the variations of snoring sound episode durations, separations and average powers in simple snorers and in obstructive sleep apnoea (OSA) patients. The goal was to explore the possibility of distinguishing among simple snorers and OSA patients using only sleep sound recordings of individuals and to ultimately eliminate the need for spending a whole night in the clinic for polysomnographic recording. Sequences that contain snoring episode durations (SED), snoring episode separations (SES) and average snoring episode powers (SEP) were constructed from snoring sound recordings of 30 individuals (18 simple snorers and 12 OSA patients) who were also under polysomnographic recording in Gülhane Military Medical Academy Sleep Studies Laboratory (GMMA-SSL), Ankara, Turkey. Snore regularity is quantified in terms of mean, standard deviation and coefficient of variation values for the SED, SES and SEP sequences. In all three of these sequences, OSA patients' data displayed a higher variation than those of simple snorers. To exclude the effects of slow variations in the base-line of these sequences, new sequences that contain the coefficient of variation of the sample values in a 'short' signal frame, i.e., short time coefficient of variation (STCV) sequences, were defined. The mean, the standard deviation and the coefficient of variation values calculated from the STCV sequences displayed a stronger potential to distinguish among simple snorers and OSA patients than those obtained from the SED, SES and SEP sequences themselves. Spider charts were used to jointly visualize the three parameters, i.e., the mean, the standard deviation and the coefficient of variation values of the SED, SES and SEP sequences, and the corresponding STCV sequences as two-dimensional plots. Our observations showed that the statistical parameters obtained from the SED and SES sequences, and the corresponding STCV sequences, possessed a strong potential to distinguish among simple snorers and OSA patients, both marginally, i.e., when the parameters are examined individually, and jointly. The parameters obtained from the SEP sequences and the corresponding STCV sequences, on the other hand, did not have a strong discrimination capability. However, the joint behaviour of these parameters showed some potential to distinguish among simple snorers and OSA patients.
authors.affiliation: Electrical and Electronics Engineering Department, Middle East Technical University, 06530, Ankara, Turkey.
authors.forename: M
authors.initials: M
authors.lastname: Cavusoglu
authors.forename: T
authors.initials: T
authors.lastname: Ciloglu
authors.forename: Y
authors.initials: Y
authors.lastname: Serinagaoglu
authors.forename: M
authors.initials: M
authors.lastname: Kamasak
authors.forename: O
authors.initials: O
authors.lastname: Erogul
authors.forename: T
authors.initials: T
authors.lastname: Akcam
mesh_terms: D000465:Algorithms; D015992:Body Mass Index; D003627:Data Interpretation, Statistical; D016208:Databases, Factual; D006801:Humans; D012891:Sleep Apnea Syndromes / Q000150:complications / Q000175:diagnosis*; D012913:Snoring / Q000175:diagnosis* / Q000209:etiology