Snoring is common in people with obstructive sleep apnea (OSA). Although not every snorer has OSA or vice-versa, many studies attempt to use snoring sounds for classification of people into two groups of OSA and simple snorers. This paper discusses the relationship between snorers’ anthropometric parameters and statistical characteristics of snoring sound (SS) and also reports on classification accuracies of methods using SS features for screening OSA from simple snorers when anthropometric parameters are either matched or unmatched. Tracheal respiratory sounds were collected from 60 snorers simultaneously with full-night Polysomnography (PSG). Energy, formant frequency, Skewness and Kurtosis were calculated from the SS segments. We also defined and calculated two features: Median Bifrequency (MBF), and projected MBF (PMBF). The statistical relationship between the extracted features and anthropometric parameters such as height, Body Mass Index (BMI), age, gender, and Apnea -Hypopnea Index (AHI) were investigated. The results showed that the SS features were not only sensitive to AHI but also to height, BMI and gender. Next, we performed two experiments to classify patients with Obstructive Sleep Apnea (OSA) and simple snorers: Experiment A: a small group of participants (22 OSA and 6 simple snorers) with matched height, BMI, and gender were selected and classified using Na?ve Bayes classifier, and Experiment B: the same number of participants with unmatched height, BMI, and gender were chosen for classification. A sensitivity of 93.2% (87.5%) and specificity of 88.4% (86.3%) was achieved for the matched (unmatched) groups.
KeywordsSnoring Sound (SS) SegmentHigher Order StatisticBispectrumMedian BifrequencySkewnessProjected Median BifrequencyEnergy
Hoffstein, V. (2002) Apnea and snoring: State of the art and future directions. Acta Otorhinolaryngol Belg, 56, 205-236.
Lee, B., Hill, P., Osborne, J. and Osman, E. (1999) A simple audio data logger for objective assessment of snoring in the home. Physiological Measurement, 20, 119-127. doi:10.1088/0967-3334/20/2/001
Dalmasso, F. and Prota, R. (1996) Snoring: Analysis, measurement, clinical implications and applications. European Respiratory Journal, 9, 146-159. doi:10.1183/09031936.96.09010146
Sola-Soler, J., Jane, R., Fiz, J. and Morera, J. (2003) Spectral envelope analysis in snoring signals from simple snorers and patients with obstructive sleep apnea. IEEE- EMBS, Cancun, Mexico, 2527-2530.
Abeyratne, U., Karunajeewa, A. and Hukins, C. (2007) Mixed-phase modeling in snore sound analysis. Medical and Biological Engineering and Computing, 45, 791-806. doi:10.1007/s11517-007-0186-x
Beck, R., Odeh, M., Oliven, A. and Gavriely, N. (1995) The acoustic properties of snores. European Respiratory Journal, 8, 2120-2128. doi:10.1183/09031936.95.08122120
Fackrell. J.W.A. (1996) Bispectral analysis of speech signals. Edinburgh Research Archive, University of Edinburgh.
Ng, A.K., Wong, K.Y., Tan, C.H. and Koh, T.S. (2007) Bispectral analysis of snore signals for obstructive sleep apnea detection. Proceedings of the 29th Annual International Conference of the IEEE EMBS, 6195-6198.
Ng, A., Koh, T., Abeyratne, U. and Puvanendran, K. (2009) Investigation of obstructive sleep apnea using nonlinear mode interactions in nonstationary snore signals. Annals of Biomedical Engineering, 37, 1796-1806. doi:10.1007/s10439-009-9744-8
Kendall, M.G. (1938) A New Measure of Rank Correlation. Biometrika, 30, 81-93. doi:10.2307/2332226
Kvam, P.H. and Vidakovic, B. (2007) Nonparametric statistics with applications to science and engineering. Wiley-Interscience. doi:10.1002/9780470168707
Searle, S.R. (1971) Linear models. John Wiley & Sons, Inc, New York.
Yadollahi, A. and Moussavi, Z. (2009) Acoustic obstructive sleep apnea detection. Engineering in Medicine and Biology Society, EMBC 2009. Annual International Conference of the IEEE, 7110-7113.
Azarbarzin, A. and Moussavi, Z. (2011) Automatic and unsupervised snore sound extraction from respiratory sound signals. IEEE Transactions on Biomedical Engineering, 58, 1156-1162. doi:10.1109/TBME.2010.2061846
Brillinger, D.R. (1965) An introduction to polyspectra. The Annals of Mathematical Statistics, 36, 1351-1374. doi:10.1214/aoms/1177699896
Hinich, M.J. (1982) Testing for gaussianity and linearity of a stationary time series. Journal of Time Series Analysis, 3, 169-176. doi:10.1111/j.1467-9892.1982.tb00339.x
Brillinger, D.R. and Rosenblatt, M. (1967) Computation and interpretation of k-th order spectra. Spectral Analysis of Time Series, 189-232.
Hinich, M.J. and Wolinsky, M.A. (1988) A test for aliasing using bispectral analysis. Journal of the American Statistical Association, 83, 499-502.
Swami, A., Mendel, J.M. and Nikias, C.L. (1998) Higher-order spectral analysis toolbox user’s guide. Version 2.
Proakis, J.G. and Manolakis, D.K. (2006) Digital signal processing. 4th Edition, Prentice Hall, New York.
Markel, J. (1972) Digital inverse filtering—A new tool for formant trajectory estimation. IEEE Transactions on Audio and Electroacoustics, 20, 129-137. doi:10.1109/TAU.1972.1162367
Hogg, R., Craig, A. and Mckean, J. (2004) Introduction to mathematical statistics. Prentice Hall, New York.
Silverman, B.W. (1986) Density estimation for statistics and data analysis. Chapman and Hall, London.
Burman, P. (1989) A comparative study of ordinary cross-validation, v-fold cross-validation and the repeated learning-testing methods. Biometrika, 76, 503-514.
Venter, J.H. and Snyman, J.L.J. (1995) A note on the generalised Cross-Validation Criterion in Linear Model Selection. Biometrika, 82, 215-219. doi:10.1093/biomet/82.1.215
Nakano, H., Ikeda, T., Hayashi, M., Ohshima, E. and Onizuka, A. (2003) Effects of body position on snoring in apneic and nonapneic snorers. Sleep, 26, 169-172.
Sanchez, I. and Pasterkamp, H. (1993) Tracheal sound spectra depend on body height. American Journal of Respiratory and Critical Care Medicine, 148, 1083-1087. doi:10.1164/ajrccm/148.4_Pt_1.1083
Kraman, S., Pasterkamp, H., Kompis, M., Takase, M. and Wodicka, G. (1998) Effects of breathing pathways on tracheal sound spectral features. Respiration Physiology, 111, 295-300. doi:10.1016/S0034-5687(97)00113-8
Young, T., Palta, M., Dempsey, J., Skatrud, J., Weber, S. and Badr, S. (1993) The occurrence of sleep-disordered breathing among middle-aged adults. New England Journal of Medicine, 328, 1230-1235. doi:10.1056/NEJM199304293281704
Mortimore, I.L., Marshall, I., Wraith, P.K., Sellar, R.J. and Douglas, N.J. (1998) Neck and total body fat deposition in nonobese and obese patients with sleep apnea compared with that in control subjects. American Journal of Respiratory and Critical Care Medicine, 157, 280-283.
De Sousa, A.G., Cercato, C., Mancini, M.C. and Halpern, A. (2008) Obesity and obstructive sleep apnea-hypopnea syndrome. Obesity Reviews, 9, 340-354. doi:10.1111/j.1467-789X.2008.00478.x
Gavriely, N., Nissan, M., Rubin, A.H. and Cugell, D.W. (1995) Spectral characteristics of chest wall breath sounds in normal subjects. Thorax, 50, 1292-1300. doi:10.1136/thx.50.12.1292
Gross, V., Dittmar, A., Penzel, T., Schuttler, F. and von Wichert, P. (2000) The Relationship between normal lung sounds, age, and gender. American Journal of Respiratory and Critical Care Medicine, 162, 905-909.
White, D.P., Lombard, R.M., Cadieux, R.J. and Zwillich, C.W. (1985) Pharyngeal resistance in normal humans: influence of gender, age, and obesity. Journal of Applied Physiology, 58, 365-371.
Brooks, L.J. and Strohl, K.P. (1992) Size and mechanical properties of the pharynx in healthy men and women. American Journal of Respiratory and Critical Care Medicine, 146, 1394-1397.
Schwab, R., Gupta, K., Gefter, W., Metzger, L., Hoffman, E. and Pack, A. (1995) Upper airway and soft tissue anatomy in normal subjects and patients with sleep-disordered breathing. Significance of the lateral pharyngeal walls. American Journal of Respiratory and Critical Care Medicine, 152, 1673-1689.