Dana C. Massie
E-mu Systems, Inc., P.O. 660015, Scotts Valley, CA 95067-0015
Sampling musical instruments are a powerful resource for virtual environment sound generators. Samplers provide real-time multi-channel playback of digitized audio signals such as individual musical instrument notes or sound effects, under control of real-time user input devices, such as a music keyboard or computer. Samplers also transform the sound through pitch shifting, time-varying amplitude modification (enveloping), filtering, and looping or repeating a section of the sound to create an indefinite sustain from a short representative segment. Interactive simulators can exploit these transformations; pitch shifting can simulate Doppler shift for moving sound sources, and simple models of spatialization can be implemented using amplitude and time delay panning and low-pass filtering. Sampling is analogous to image processing in computer graphics; digitizing and processing of real images (or sounds) may be faster than developing a synthetic model, if the model is even feasible. Sampling and its extensions may thus always offer an advantage over pure model-based approaches.