The lung sound data of our laboratory were provided by the first affifiliated hospital of Xiamen University, China. A self-made double channel electronic stethoscope used in the collection of lung sounds (the stethoscope has been examined and authorized by the State Intellectual Property Office; patent name: Electronic stethoscope with active noise reduction and auxiliary diagnosis function; China.Patent: CN105496447B, 2019-02-05.). The electronic stethoscope can collect the breath sound and background interference noise when the mic direction of the main channel is inward, and the mic direction of the auxiliary channel is outward. Since the frequency range of normal and abnormal breath sounds is basically lower than 2 kHz, the audio samples stored in the dual channel are first passed through a low-pass filter with an upper limit frequency of 2 kHz to filter out the interference of high-frequency noise and thermal noise in the audio signal. After that, the filtered dual channel files are input into the adaptive noise cancellation (ANC). After a series of algorithm processing, the noise of the main channel minus the noise of the sub channel is realized, and only the enhanced single channel breath sound files are left. Here we show part of the lung sound audio before and after noise reduction. Among them, before means audio before ANC, and after means audio after ANC.

For example: Normal 1-before ANC represents the audio before ANC processing (normal lung sound); Normal 1-before ANC (Major) represents the audio collected by the main channel of stethoscope; Normal 1-before ANC (sub) represents the audio collected by the auxiliary channel of stethoscope; Normal 1-after ANC represents the audio after ANC processing (normal lung sound). 

Normal1-after ANC

Normal1-before ANC (major)

Normal1-before ANC （sub）

Normal1-before ANC

Normal2-after ANC

Normal2-before ANC (major)

Normal2-before ANC （sub）

Normal2-before ANC

Rhonchus-after ANC

Rhonchus-before ANC (major)

Rhonchus-before ANC （sub）

Rhonchus-before ANC

Wheeze-after ANC

Weeze-before ANC(major)

Weeze-before ANC（sub）

Weeze-before ANC