Study On The Technology Of Portable Lung Sound Acquisition

Lung sound is a general term of sounds which is generated by respiratoryventilation process, contains the pathology of the respiratory system, and physiologicalinformation. As a simple inspection tool, stethoscope is still widely using in the lungsounds auscultation. Restricted by doctor’s subjective orientation and non-quantitativediagnosis technique, traditional auscultation method rough at clinical diagnosis, anduseful information from lung sound can not be fully and accurately exploited. With SDcard storage carrier, the lung sound acquisition system based on STM32records data ofpatient’s lung sounds, then it’s easy to observe the lung sound waveform curve from acomputer, comparing it with historical records, and also to offer the possibility forremote treatment.STM32microcontroller as part of the main chip in the system, uses a module forcircuit design. It includes preamplifier filter module, sound module, voltage regulatormodule, collection and storage modules, circuit design and driver design.System implementation. conversion from lung sound signal to electrical signalreached by electret condenser microphone. Enlarged active filter circuit and headphonedriver circuit realized by single power supply chips TLV2334and TPA711. Data arestored in text format to the SD card via SDIO interface. Reader or laptop computercomes with an SD card interface, you can transfer data from the SD card to yourcomputer.After SD card data has been transferred to the computer, first of all, two-channeldata were recovered to the sound, and the effect listened and evaluted, then the data gothrough a low-pass filter designed by Matlab. Finally, wavelet and wavelet packet areused to process the signal, pure lung sounds are obtined. Patient experimental data usedin the paper arecollected in the clinical and compared with normal lung sounds, thecharacteristics and differences in spectrum between normal subjects and patients areobtained.