This paper describes the use of the hidden-operator technique, also known as the Wizard-of-Oz technique, in the context of development of speech input for an existing software tool, normally operated by function keys over a keyboard. The program allows the conversion of CAD drawings in a form suitable for CNC machines. Part of the conversion can be done automatically, but other aspects of the conversion require professional knowledge. The results so far confirm our belief, that the hidden-operator technique is an effective method for detecting in an early phase of design user problems and user reactions on simulated perfect speech recognition. Keywords: speech assessment, formative evaluation, hidden-operator technique, Wizard of Oz, audio-visual protocolling, multimodal interaction, CAD
Bibliographic reference. Vossen, Paulus H. (1991): "Evaluating speech input and output in a CAD-system using the hidden-operator method", In EUROSPEECH-1991, 69-72.