Eli Polonsky
Walk of Fame Participant
AM Stereo doesn't address the issues of frequency response, interference, or noise.
AM stereo doesn't address interference or noise, but if you have a wideband AM stereo receiver such as some that were made in the '80s and '90s, and you're in a spot where you're getting a clean signal on an AM stereo station broadcasting music in the full allowable spectrum, the frequency response on analog AM stereo can be far better than you'd believe if you haven't heard it.
I still have wideband AM stereo receivers from the '80s and '90s, and live close enough to 740 WJIB for it to sound amazing (for AM) in wideband AM stereo, just about as good as FM analog stereo. I don't know what the high end limit is, but it sounds like it goes over 10 kHz.
Some of today's HD radios have chips to decode analog AM stereo, but unfortunately with the same limited frequency response as the analog AM, probably rolling off at well under 5 kHz. They don't have wideband AM stereo like some of the '80s and '90s analog receivers.