My sister returned from studying abroad for a health check-up. She temporarily came back home and asked her brother, who is a medical student, to do a simple health check on her... Her brother placed the stethoscope on her chest and tilted his head. It seems he confirmed multiple heartbeats... Moreover, they were completely different from human heart sounds... To confirm the abnormality, her brother performed a palpation... However, he couldn't find any cause at all...
