Mine started with a heart murmur which was followed by my cardiologist for years until it got to the point where I needed the valve replaced. It was replaced with a pig valve in 2019. I’m doing great at age 77.
There are actually 4 ‘sounds’ called ‘S’ but when listening, usually only the S1 & S2 can be heard as they are typically in sync with the S3 and S4. Recall that there are 4 chambers of the heart, 2 Atrium and 2 Ventricles, each opening and closing repeatedly.
The sounds of an AS really do sound like a murmur, but it is often not the case. FWIW, I as well have had an AVR, but I have experience in the field and the Docs, NPs, and Nurses are typically surprised at my understanding of my conditions.