There's a Littmann app that has a collection of lung and heart sounds that might be worth your time. I haven't used it myself, so I don't know how good it is. As an inexperienced M1, I'm still pretending I put the stethoscope on the right places and can hear any sounds at all.
How do I use a stethoscope? The 3M Littmann Learning Institute App is an auscultation training app with heart sounds, lung sounds, and patient histories.