Spatializer is a binaural spatialization plugin. It processes the sound to give the feeling that it comes from a particular direction. It sets the position of the sound source in space and uses an HRTF (head-related transfer function) to compute the result by convolution.
This is more than just a simple pan processing, firstly because the feeling of location is rendered all around the head (in front, behind, several heights...). Secondly, the sound processing takes the shape of the human ear into account.
The sound processed by the plugin is designed to be listened using headphones to get an optimal result.
The plugin provides a parameter to change the width of the sound source and give the feeling that the sound comes from a narrower or wider sound source.