Subtle whistling sound between 50-60 mph; also audio issue

I've had my 2016 LT, which I bought used, for about three months. I've put over 6,000 miles on it, and love it. Now has about 23,000 miles on the clock.

I'm starting to notice two issues, both of which I will have dealer investigate, but neither of which I've seen any info on these forums that seems to be relevant:

1. A subtle, reverberating, whistling sound coming from the front left of the vehicle, but only at certain speeds, and only under certain load conditions (foot on accelerator, level or going uphill, etc). If I take my foot off the accelerator to coast, or if I start downhill, or even if I change speeds by 1 mph, it can disappear instantly. Below about 52-53 mph, or above 60-61 mph, it goes away instantly. It's not very loud (turn up the radio to 20-25 and you can't hear it anymore), but it's very distinct. Makes me think of a small plastic fan blade spinning, but not properly lubricated (probably because the cabin air fan in my old Saturn Ion made a similar sound on speeds 3 or 4). But this is clearly drivetrain related. And it's definitely there in electric mode, but I'm not sure honestly if it's still there in gas mode.

2. Every once in a while, the audio system will sound as if one of the speakers suddenly stopped working, or perhaps the tone settings changed (as if the treble were turned way down). I've turned off the auto volume adjust to eliminate that variable, and I've adjusted audio settings to only one speaker at a time, and I never been able to pinpoint which speaker it might be, if that's what it is. If it was a loose wire I would expect to hear a crackling/popping sound, but I don't. It's very intermittent, but also very annoying when it does happen. I can't determine any consistency in the circumstances that cause it, and I don't see this one being easy for the dealer to replicate or diagnose.

Any thoughts?