Reading about lung sounds is not enough. You have to hear them. Pick a sound, hit play, and listen while the waveform scrolls by. Each sound points to a different problem. Turn your volume up.
The stethoscope
The green line sweeps across like a monitor. Each sound has its own shape: steady, whistling, crackly, or rumbling.
tap a sound, then play
Pick a sound to begin.
Note: these sounds are made by the computer, so they are close copies built to train your ear for the pattern. A real chest sounds richer than this, but the rhythm and the pitch match.