Strange overtones in a recording
I have recorded my practice with an iphone 5SE (and it's built in toy microphone). Somehow the recording picked up some sympathetic overtones, that sound like someone whistling along my playing. The recording was not tampered with, sound was not altered - it's as raw as it gets.
Not everyone can hear them (even with good earphones), but I was wandering if there is a rational explanation behind this phenomenon.
I should point out that I was not in the center of the room and that phone was tilted, so standing waves should not be that obvious. The violin itself does not emit the whistling noises either. It must be something in the way this microphone picks the sound up.
I think it may be one of those situations where more than one thing is affecting the sound. I can clearly hear the resonance of the room in the recording, and tilting the phone or standing somewhere other than the center of the room isn't really going to change how the room sounds, which in this case is not ideal. So the first thing I would try is to record in any other space and see if the phenomenon is repeated. I also hear what sounds like maybe a bit of distortion in the preamps of the microphone in the recorder, or at some stage in the signal path. If you can adjust the gain there, that might be a thing to try. Or move the unit further away from you, and maybe try above the violin rather than underneath from the side. There's a harshness to the microphone sound that is what you can get from a small-diaphragm condenser mic, especially if it's too close to the violin. If I close-mic a violin, I generally use a ribbon mic for that reason. Still, you sound good, and I will listen to solo Bach all day.
Look up "comb filtering". You might have a bit of that, moving. Or not...
I don't hear whistling with my 70 yo ears, but in the past I have had harmonic distortion from a built-in mic, especially in double stops.