  When operating a machine, the operator needs to know some spatial relations,
like the relative location of the target or the nearest obstacle. Often,
sensors are used to derive this spatial information, and visual displays are
deployed as interfaces to communicate this information to the operator. In this
paper, we present psychoacoustic sonification as an alternative interface for
human-machine interaction. Instead of visualizations, an interactive sound
guides the operator to the desired target location, or helps her avoid
obstacles in space. By considering psychoacoustics --- i.e., the relationship
between the physical and the perceptual attributes of sound --- in the audio
signal processing, we can communicate precisely and unambiguously interpretable
direction and distance cues along three orthogonal axes to a user. We present
exemplary use cases from various application areas where users can benefit from
psychoacoustic sonification.
