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A Weakly Intrusive Ambient Soundscape for Signaling and Intuitive State Perception Fredrik Kilander & Peter Lönnqvist Department of Computer and Systems Sciences, Stockholm University/KTH Electrum 230, SE-164 40 Kista, Sweden {fk, peterl}@dsv.su.se Introduction The use of audio cues in computer interfaces has seen a remarkable development in recent years with the general proliferation of soundcards and sound sources. The audio schemes in the Microsoft Windows operating systems, for example, offer the association between a rich set of system events and sounds. The events most commonly encountered are, perhaps, login and logoff events, notification of new email and the proverbial beep when something goes wrong. All these events, however, are closely tied to events and changes of state which are either obvious anyway, or without sufficient resolution to avoid being a nuisance. In this paper we present WISP, the concept of an ambient soundscape in which events and states in the computing and physical environment are reflected in the form of next to non-intrusive audio cues. A WISP is meant to service a physical space, like a personal office or a common room. The listening experience is intended to convey intuition rather than interruption; each signal should be sufficiently non-intrusive to be accepted without disturbing the focus of the task at hand, while distinctive enough to be separable from the other cues. The selection of auditory messages that humans choose to process can be seen as depending on context rather than physical characteristics (Anderson, 1995). At a cocktail party we can follow one conversation, but as we hear our name mentioned in another conversation our focus is suddenly changed. Thus we can say that auditory messages that bear meaning are the ones grasping our attention. Meaning in this sense might not always be mapped to semantics, but might as well be learned. For instance, when the sound of the telephone is heard, we know that someone probably are calling us. Auditory messages of this type are often quite disturbing, and it is also their intention to be so, to be able to grasp our attention. We propose more non-intrusive auditory messages and predict that if we map meaning to these they might be just as useful without disturbing the user in the same way as a phone signal might do, and they might even be comfortable to listen to. Choosing sounds For our prototype we elected to work with natural sounds. We recognize that human reaction to sound is individual and culturally motivated, it is therefore important to emphasize that no particular set of non-intrusive natural sounds is a priori more suitable than others. Still, we believe that the selection of natural sounding soundscapes can be narrowed down to an environment in which the WISP is not perceived as noise pollution. In order to provide support for both discrete events and long-term state intuition, we are interested in both short sounds and backdrops which can be conveniently looped without sounding artificial. Short sounds, i.e. sounds with discrete playback times, can of course be quite long. The sound of rolling thunder, for example, may be of several seconds duration. As a starting point we explore the sounds of the forest. These include many possible variations which include both natural and manmade audio cues. Birdcalls from various species, insects, the sound of wind, rainfall and thunder are all immediately available. Manmade sounds include trains, planes and automobiles passing in the distance as well as church-bells and the occasional far voice, although the latter two are probably to craving of attention to be non-intrusive. Before we go on to the usage of these sounds in a WISP, we should recognize other soundscapes of interest. The sounds of a city provide a powerful backdrop on which to project suitable signals: traffic, car horns, passing music, dogs etc. Likewise, the seashore, a train station or an airport should provide interesting avenues of exploration. Common to these manmade environments is that they are generally much more noisy than a forest, which may work to be counter the intended effect of the WISP, namely that it should not pollute the natural environment. A personal WISP in use In this section we will sometimes assume that availability of a localizer service that can be queried for the location of people. The WISP concept is no way dependent on such information, but the particular application we like to use in the example is. Co-worker presence We could, for example, associate the presence of selected co-workers with certain bird calls and playback frequencies. The net effect is that as more and more colleagues arrive at work, the WISP forest fills up with birds. Rather than consciously watching for a particular sound, the listener is expected to acquire an intuition for the number of coworkers present (and presumably out of sight). Email inbox state The simple arrival of yet another mail is in many cases not reason enough to disrupt ones work. While the notification may often be welcome, it can also be perceived as intrusive and stressful. Because of this, we explore the possibility of using the WISP to convey more information about the waiting mail. A classifier scans the waiting mail and provides the wisp with categories of email: personal mail, mailing-list submissions and suspected spam. Each category then results in a different sound cue which may be either looped or repeated with a certain intensity. The net result is that the listener is bestowed an intuition of the expected contents of the unread mail, rather than the interruption of each new message. A shared WISP The deployment of a WISP in a shared space, like a meeting room or kitchen is escorted with issues of how to join the preferences of several people when each is to be catered by a single WISP (again we assume a localization service which tracks the movement of people within a building). One imme- diate conclusion is that users of the shared WISP also subscribe to a shared set of available notifications. In this way, each notification is associated with a single sound, forcing listeners to share sound cues. This greatly reduces the possibility that users confuse a certain cue with different semantics. It also allows the WISP to join events directed at several subscribers into a single playback event. Another property of a shared WISP is that it becomes a broadcast environment. With the sound available for everyone to hear it becomes difficult to aim particular cues at a single person. This in turn makes it important to look at the risk of the WISP as a source of noise pollution. For example, when a group which does not subscribe to the services of a present WISP suddenly is joined by a heavy subscriber, the group may be annoyed by the sudden presence of audio cues. To counter this, the WISP should allow users to be subscribers to silence as well as sound. Technology We have implemented a simple WISP in Java. The audio playback features of JDK 1.2 offers simultaneous playback of up to 64 channels of sampled sound (or MIDI data which we do not use). At the time of this writing an email state provider is being prepared. References Anderson, J. R., (1995), Cognitive Psychology and its Implications (Fourth Edition), New York: W.H. Freeman and Company. Ishii, H., Wisneski, C., Brave, S., Dahley, A., Gorbet, M., Ullmer, B., and Yarin, P., ambiemtROOM: Integrating Ambient Media with Architectural Space, in Proceedings of CHI '98, ACM, New York, pp. 173-174.