Human interaction is enriched by the redundancy of multimodal communication.
But as the turn of the century approaches, computers have the ability to talk, listen, and, perhaps, even understand. Integrating new modalities like speech into human-computer interaction requires rethinking how applications are designed in today's world of visual computing. It can also manipulate information about the real world rather than the real world itself. These two capabilities have promoted the development of a large variety of computer-based scientific instruments. But a serious consequence of relying exclusively on the ubiquitous visual interface is that these tools are difficult, if not impossible, to use in an eyes-free environment.