Humans eat and digest food among different tracts around their body for survival. Once a meal is ingested, it passes through the esophagus, stomach, and small intestine. The small intestine absorbs nutrition earnestly. It performs a peristaltic motion to pass down the contents, which are known to produce characteristic sounds, call "bowel sounds." The frequency of small intestines' movement correlates to the number of sounds it makes; therefore, the "bowel sounds" in the medical field are mostly used to diagnose intestinal obstruction or to nurse bedridden patients. In today's medical field, a doctor uses a stethoscope for a period to diagnose the patient. However, this method relies much on experience and intuition, and it is difficult for longtime testing. It is very important to provide optimum nutritional quantity at the right time to a bedridden patient in the intensive care unit (ICU). This is because providing nutrition very late or even a gram more than required may cause malnutrition or indigestion. Therefore, by using a small microphone, the progression of the number of bowel sounds per unit time can be monitored automatically; this has succeeded in diagnosing the digestive activity of the small intestines. In this research, we propose a new diagnosis method called "two-step template matching," in which a computer is used for automatically diagnosing bowel sounds stably in real time, even under noisy environments like that of an ICU.