|Abstract|| ||OpenSoundEdit is a sound-editing system that provides a unified three-dimensional user interface to edit complex sounds composed from different representations. Sounds are mapped onto a single three-dimensional space representing time, amplitude and a view-dependent third dimension (e.g., frequency, channel number, etc.) Sounds can be edited by direct manipulation on the 3D display window or using additional representation-specific controls. As the user edits sounds, changes can be heard through a synthesis server, an application that generates sound in response to commands supplied by OSE. OSE is implemented using extensible, multi-platform technologies. This paper illustrates the features of OSE with sinusoidal-track and resonance models.