We have not done bowel auscultation in a clinical setting yet so I'm not positive. I know I had a lot of trouble with my old $20 stethoscope auscultating the apical pulse, but I hear it clearly even with a lot of background noise with my classic 3. Another thing to take into consideration, our ears are not "trained" to pick up everything while auscultating, so no matter which one you pick it's going to take time and practice. If you're really worried about picking the right stethoscope, you can always ask your professors, they know what works.