Thanks for the heads up, jeepster. This may prove helpful for folks down the road.
What is happening is the speech engine is suddenly not receiving any audio signal - opening and clicking, 'OK' on the Options screen resets the speech engine (and other items, regardless of whether or not you make changes - hitting 'Cancel' will do nothing). Not sure if G Hub is muting the device, changing devices around or if it's just knocking the speech instance out of sorts. Glad you got it figured out!