In this paper, we report one of the methods to distinguish patient’s atelectasis condition from the normal condition based on the spectral analysis of the auscultation by the electric stethoscope. Atelectasis is a respiratory collapse defined as the lack of gas exchange within alveoli, and due to airway obstruction, or compression of the lung. This atelectasis condition is conventionally founded as the asymmetric sounds of the left lung area and right one by auscultation using air-conducted stethoscope. We aimed to this auscultation diagnose objectively. We assume that the cumulative sound powers of auscultation sound relate the air-flow volume of the respiratory, and show the power spectrums of auscultation sounds in several cases of respiratory types. The results show that the left-right symmetry of the sound’s powers decreases in the atelectasis cases
