Heart sounds separation from lung sounds using independent component analysis

Heart beat is an unavoidable source of interference during lung sound recording. This disturbance is more significant at low and medium breathing flow rates. Removing heart sounds (HS) from lung sound recordings or vice versa is a challenging task but of great interest for respiratory specialists and cardiologists. In this study, to separate the two signals, a novel HS separation method based on Independent Component Analysis (ICA) is developed. This method applies an ICA algorithm to the spectrograms of two simultaneous lung sound recordings obtained at two different locations on the chest and yields the independent spectrograms of the separated signals. Then, by implementing the Inverse Short Time Fourier Transform (ISTFT), the separated signals are reconstructed in the time domain. The method was applied to data of two healthy subjects. Analysis of the results as well as subjective inspections indicate the efficiency of the proposed method in terms of HS separation from lung sounds.