Before revision:  These systems are therefore confined to producing either acoustically-linked beat gestures or semantically-linked gesticulation (e.g., raising a hand when saying ``high'' ): they cannot appropriately learn to generate both gesture types.
After revision:  These systems are therefore confined to producing either acoustically-linked beat gestures or semantically-linked gesticulation (e.g., raising a hand when saying "high" ): they cannot appropriately learn to generate both gesture types.