Murmurs have a swooshing sounds that gets louder as things get worse. I was in the know of the murmur swooshing sound since I was 8 years old, watching the cardio reacting and getting a child's education on the repair. I had replacement aortic valve done at age 36 and it was a loud swooshing sound, made my jaw drop when I heard it. It was pretty bad, that is what the doctor hears through a stethoscope. Just think of a person who has heard her valve getting bad over the years. I was informed by the surgeon and kept up with the cardio since surgery. Education and asking question is the key to keeping up.My GPs listen to my heart and tell me it sounds good. Same thing with my cardiologist. I believe there are certain valve problems that can be heard with the stethoscope. They don't need to have heard your heart before to hear something out of the ordinary, but they do probably have to know what a mechanical valve sounds like. When I was in the hospital, there was more than one intern that wanted to hear my valve both before the AVR and after the AVR to learn what a crapped out valve sounds like and to learn what a new mechanical valve sounds like.
The echocardiogram will help them know what's causing the new sound and if there is cause to take action.