![]() ![]() The location of the generation of the wheezing sounds includes the branches between the second and seventh generation of the airway tree coupled with the oscillation of air molecules passing through narrowed airway walls. The most common condition of wheezing observed in people is the expiratory wheezing (EW), where the wheezing sound is heard during the exhalation. The nature of the obstruction decides the nature of the wheezing, i.e., the occupancy of a flexible obstruction in the air passage causes inspiratory or expiratory wheezing whereas, a rigid permanent obstruction produces a wheezing sound throughout the respiration. The bronchial obstruction due to tumours, accumulation of mucus or any other secretions, bronchostenosis by inflammation or the presence of foreign bodies results in the generation of wheezing sound. They can be high or low pitched depending on the narrowing of the airway obstructions. Wheezing sounds are musical sounds that can be identified by their intensity, pitch, location, and time duration between expiration and inspiration. ![]() In the present study, an attempt is made to bring out the hidden complexities in the adventitious and continuous respiratory disease-Expiratory Wheeze (EW). Thus, many significant, characteristic features and conditions of the lung can be understood from the auscultation of lung sounds. When the continuous adventitious breath sounds (wheezes, stridor, and rhonchi are musical) exhibit a time duration of > 250 ms, the discontinuous adventitious signals show a time duration of < 25 ms. ![]() Adventitious sounds can be generally classified as continuous and discontinuous based on their duration of occurrence. In the normal lung sounds, the vesicular sounds (VS) are heard over the chest wall distant from larger airways. When the normal lung sounds are generated due to the movement of air through the tracheobronchial tree, the vibrations of solid tissues, are responsible for the adventitious or abnormal lung sounds. Based on the frequency, intensity, time duration, and quality of the sound, a pathological and healthy-normal breath signal can be distinguished. Respiratory diseases are one among the leading cause of deaths in the world, which is usually diagnosed through auscultation. The feature extraction of the power spectral density data and the application of principal component analysis helps in distinguishing vesicular and expiratory wheezing and thereby, giving a ray of hope in accomplishing an early detection of pulmonary diseases through sound signal analysis. An investigation of the dynamics of air molecules during respiration using phase portrait, Lyapunov exponent, sample entropy, fractal dimension, and Hurst exponent helps in understanding the degree of complexity arising due to the presence of mucus secretions and constrictions in the respiratory airways. Thirty-five signals of vesicular and expiratory wheezing breath sound, subjected to spectral analyses shows a clear distinction in terms of time duration, intensity, and the number of frequency components. ![]() The pulmonary pathological symptoms reflected through the lung sound opens a possibility of detection through auscultation and of employing spectral, fractal, nonlinear time series and principal component analyses. Since the outbreak of the pandemic Coronavirus Disease 2019, the world is in search of novel non-invasive methods for safer and early detection of lung diseases. ![]()
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