an embodiment of the invention provides a method of diagnosing obstructive sleep apnea , the method comprising : acquiring a sleep sound signal comprising sounds made by a person during sleep ; detecting a plurality of snore sounds in the sleep sound signal ; determining a set of mel - frequency cepstral coefficients for each of the snore sounds ; determining a characterizing feature for the sleep sound signal responsive to a sum of the variances of the cepstral coefficients ; and using the characterizing feature to diagnose obstructive sleep apnea in the person .