heart sound

例句：

1. 1.He listened to the heart sound of his own blood.
   他倾听着自己血液的心跳声。
2. 2.The doctor could hear the heart sound through her chest.
   医生可以通过她的胸部听到心脏的声音。
3. 3.The old man's heart sound was weak and irregular.
   老人的心跳声弱而不规则。