This chapter covers the wide field of spatial effects. We start with basic effects such as panorama, the precedence effect, distance and space rendering, the doppler effect and sound trajectories. Then the most important techniques for sound projection are described, both for individual listeners using headphones and for an audience listening through a set of loudspeakers. In natural listening conditions, sounds propagate from a source to a listener modified by the environment. We refer to the kind of processing operated by the environment as reverberation. We will illustrate these kinds of effects and describe audio processing techniques that have been devised to imitate and extend the reverberation that occurs in nature. In the last section we list all the filtering effects that are designed to change the apparent source width, the spaciousness of a sound field, and the directivity of a loudspeaker set.
Keywords: Localization, Externalization, Head-related Transfer Functions, Three-dimensional Acoustics, Headphones, Loudspeakers, Reverberation, Spatial Enhancements, Sound Systems