[Neuroscience] Q on vestibular system: Acceleration or velocity?

[Mathias]

Dear ng,

I'm looking for a reference about whether the vestibular system yields 
an acceleration and/or velocity signal (e.g. used for the head direction 
and place cell system). Googling for this I found a website...
http://paperairplane.mit.edu/16.423J/Space/SBE/neurovestibular/NeuroVestibular/2_Physiology/PhysSub3.html
... that claims the vestibular system outputs a velocity and not an 
acceleration signal "over the range of normal head movements". 
Unfortunately there is no reference and I'm not even certain about which 
species they talk.

Any reference on this topic would be highly appreciated,
    Mathias