[VBox] Audio plays too fast in FreeBSD-10 and -11 guests on FreeBSD-9 host

[Yuri]

When I play sound in a FreeBSD guest, it plays noticeably faster, with 
higher pitch.
This doesn't happen in Ubuntu guest on the same host.
This happens with both mplayer and vlc players. It looks like the sound 
driver consumes audio samples faster than it should.

It looks somewhat similar to the currently open ticket 
https://www.virtualbox.org/ticket/4605 , except this ticket talks about 
different guest/host and about slower playback.

What could be a problem?

vbox-4.3.12

Yuri