Sounds are often important when people work together in groups. Builders on a construction site coordinate their activities in a common project by listening to their workmates hammering, shovelling, and revving engines. The usefulness of sounds in collaborative activities was demonstrated by an experiment in which a pair of people worked together to produce as many bottles of coke as possible in a computer game-like simulation of a factory. The factory consisted of nine interconnected machines, such as a heater, bottler, and conveyors, with on/off and rate controls. Each person was seated in a separate room and could see and control half the factory, and talk to the other person by microphone. The coworkers produced more coke when they could also hear
the status of the machines through the clanking of bottles, the boiling of water and other everyday sounds. The sounds helped them to track ongoing processes, monitor individual machines, maintain awareness of the overall condition of the factory, and talk about the factory more easily. The activity was also more enjoyable when the sounds were on (Gaver et al. 1991).