A hybrid reverberation crossfading technique

Hybrid reverberators combine convolutional and feedback delay network (FDN) reverberators to exactly reproduce the psycoacoustically important reverberation impulse response onset while efficiently generating the needed late-field characteristics. A simple method for crossfading between the convolutional and FDN components of a hybrid reverberation is presented. It involves forming the convolutional impulse response as the windowed difference between the desired and FDN impulse responses. In this way, arbitrary windows may be applied to the convolution and FDN components of the hybrid reverberator impulse response in forming the cross-fade. For applications in which the impulse response onset depends on a parameter, a singular value decomposition is used to develop a low-rank approximation to the tabulated reverberation impulse response onsets. The approximation is the combination of a few fixed impulse responses, with parameter-dependent weights. An emulation of the EMT 140 plate reverberator is presented as a sample application.