Audio is a significant factor in the design of the human computer interface in ubiquitous computing. The characteristics of the medium allow for a hands-free interaction without the need to switch the focus to a display (eyes-free). Moreover, determining the graphical capabilities of the wearable device to adapt the output to the device is not needed. But audio based interfaces are also challenging, since humans are visually oriented. The ubiquitous computing community recognized the advantages of the audio channel, but the restrictions inherent to the medium are mostly ignored. Authors of...