I think that the speaker/ mic will also be used for Ultrasonic motion tracking.
I think they'd more likely put in a small emitter like what's in those dog whistle things, rather than an ultrasonic tweeter. And those ultrasonic devices seem to be fairly directional, so that speaker placement would be on the wrong part of the controller. Even the patent shows the emitters (Tx) placed on specific parts of the controller for directional use.