What are the characteristics of the first electronic stethoscope in China?

It was an electronic stethoscope developed by the Institute of Acoustics of the Chinese Academy of Sciences in 1981 with the assistance of the Beijing Railway Hospital. This type of stethoscope is similar in appearance to an old-fashioned stethoscope, but because of its acoustic components such as miniature sensors and amplifiers on the head of the cartridge, the doctor can adjust the volume based on the patient's heart sound and the doctor's hearing. It is also equipped with four switches of different frequencies. The doctor can divide the frequency and auscultation of the noise and additional sound of different frequencies, which is beneficial to improve the auscultation effect.