Classification of Respiratory Diseases Using Respiratory Sound Analysis

Respiratory or lung sounds recorded on the chest can be used to identify different types of diseases. These sounds are attenuated by the thorax and thorax-microphone interface. In order to proper classification of respiratory diseases waveforms similar to the ones generated within the lungs must be recovered from the attenuated sounds. The equalization of crackle sounds recorded on the chest can be done for accurate classification of respiratory sounds. From an experiment an estimation of the channel attenuation was obtained according to which the equalization is applied. For that, multiple tones between 100 and 1200 Hz were applied to each subjects’ mouth where they were acquired. These tones were also recorded on the chest. The power ratio between the one measured on the chest and that measured at the mouth is used to calculate the attenuation of each tone. After obtaining the average attenuation curve a discretetime equalizer was applied to crackles acquired from patients with congestive heart failure, fibrosis, and pneumonia. The equalization is used to modify the maximum frequency and two cycle duration indices measured from these crackles. The equalizer improves the extraction of features from the crackles sounds. Equalization of crackles can be used to better classify the