This video from Husqvarna 2 years ago doesn't sound like it's a motor noise. Sounds more like an onboard beeper that can emit single tones. This, in my opinion, is rather disappointing.
It's possible that's some kind of motor noise, but it doesn't sound like it to me.
EDIT: I realize when I say "motor noise" there's some ambiguity. I know there isn't a gas powered engine in this little mower. Revving an engine is exactly what I expected, and this isn't that. When I reference motor noise here, I just mean sound could be produced by a servo or similar, but I don't think that's what's happening.
https://www.youtube.com/watch?v=p0_RPlSe344
It's possible that's some kind of motor noise, but it doesn't sound like it to me.
EDIT: I realize when I say "motor noise" there's some ambiguity. I know there isn't a gas powered engine in this little mower. Revving an engine is exactly what I expected, and this isn't that. When I reference motor noise here, I just mean sound could be produced by a servo or similar, but I don't think that's what's happening.