Patent US 6,448,846

By taking advantage of the ability to control the phase relationship between a processor's output (or portions of a processor's output) and the phase of the pre-processed signal (in a particular frequency range or ranges, a controlled accentuation or enhancement of the processor's effect can be realized. In one embodiment this is achieved by providing a gain control circuit that receives and selectively amplifies the input signal prior to it being summed with the processor's output.