The major objective of the technology is to provide a signal synchronization device, as well as a stethoscope, an auscultation information output system and a symptom diagnosis system capable of signal synchronization, which may provide synchronization for an electrocardiogram (ECG) signal and a heart sound (phonocardiogram, PCG) signal, such that both signals are synchronous in time domain. Another objective of the technology is to provide a signal synchronization device, as well as a stethoscope, an auscultation information output system and a symptom diagnosis system capable of signal synchronization, which may increase a diagnosis rate for a cardiovascular disease effectively. The proposed intelligent stethoscope has been conducted human trials in NCKU and Tainan Hospitals.Heart-sound (phonocardiogram, PCG) auscultation is a rapid and fundamental technique for examining the cardiovascular system. The main components of PCG are the first (S1) and second (S2) heart sounds. Discriminating these heart sounds under the presence of additional heart sounds and murmurs is difficult. To recognize these signals efficiently, this project proposes a monitoring system with PCG and electrocardiogram (ECG). A software application is developed on smartphones for heart-related signal recording, display, and identification. Doctors may refer to these physiological signals on the smartphone and simultaneously listen to the heart sounds to diagnose the potential heart disease. It＇s help for reducing the uncertainty existing in heart sounds and the training periods.The intelligent stethoscope can not only visualize the heart sound (phonocardiogram, PCG) signal, but also measure human＇s electrocardiogram (ECG) and PCG simultaneously. With an internet of things (IoT) system and a cloud database, the stethoscope can be used in hospitals and telemedicine. The proposed stethoscope includes three parts, a front-end device for ECG and PCG acquisition, a smart device＇s APP and a cloud server. The ECG-measuring system is designed for single lead measurement, which can send the real-time ECG data to the smart device＇s APP. The heart-sound-measuring system keeps the traditional stethoscope head to ensure doctors on the same auscultation manner. The proposed intelligent stethoscope has been conducted human trials in NCKU and Tainan Hospitals.