Head-Orientation-Based Device Selection: Are You Talking to Me?

If multiple voice-controlled devices are present in a room, it is necessary that the user can select a certain device. In this article, we present an algorithm which estimates the head orientation of the user for this purpose. The device responds only to speech commands if the user faces the device. We found two properties to be useful for estimating head orientation. First, the acoustical propagation paths, especially early reflections vary with changing head orientation. The second property is the human voice's directivity in high frequencies. The algorithm uses the global coherence field, which is modified in order to use these two properties. We evaluated the algorithm in an office room and observed correct detection rates of about 80%.