I can’t reproduce this issue on my other 2 ubuntu vbox VM’s, so it seems to be specific to whonix. When I’m playing short videos on VLC or MPV inside whonix 16.0.8.2 for vbox, I notice videos will a lot of times either be high pitched or low pitched until I restart the VM (it can take several restarts before the pitch issue goes away). I’ve tried from 10gb of RAM to 2gb of ram allocated to the VM and 2-3 CPUs allocated, but it doesn’t seem to have an effect.
Also had this issue on older whonix versions as well.
Whonix doesn’t change sound settings inside the VMs. I don’t remember anything related changing in Whonix source code. Debian, VirtualBox and/or the Linux kernel might have had related changes that I am not aware of.
You could try changing the VirtualBox host software sound audio settings.