Implement Artificial Reverberation by using filterbank methods
Zhe Shi · The Sydney eScholarship Repository (The University of Sydney) · 2016
This final review will present the digital implementation of artificial reverberation by using filterbank methods.It will mainly focus on discuss and analysis the basic digital audio principle of each component as well as the overall structure of the classical algorithmic reverberator.Sound examples will also be provided to show how reverberator produce a room support or tone color change for different instrument sounds and vocal sound. Problem descriptionReverberation is one of the most important characteristics in room acoustic quality.It is also an important component when describing tone color or tone quality of the music.The reverberation can be defined as "the persistence of sound after the original sound is produced."[2,P425-426].It determined by original sound bounced and reflected by the boundary and shape of the room.In music, a relatively longer reverberation will provide more "warmth" and "fullness" sensation.Human's voice would also benefit from a certain level of room support as well.Nevertheless, if reverberation is too long, the intelligibility of the vocal sound would decreasing.In order to measure the reverberation time, the most common way is to use an impulse response and the sound of the pistol is the most frequently-used way to create impulse response in practical.The reverberation will be treat as two separate parts: early reflection and late reverberation, both served a different purpose when defining the acoustic qualities in a room.In digital signal processing, there are two ways to produce artificial reverberation: convolution and filterbank.Convolution method is to use the impulse response that recorded in the real rooms or actual halls and then convolutes the input signal and the impulse response to create a relatively more realistic and faithful reverberation.Filterbank method, on the other hand, is to use algorithm to simulating a room model and create a imitate version of real reverberation.Since the filterbank method is a simulation, it is harder to create a natural reverberation as convolution method.However, filterbank method provides an option to doing some detailed parametric changes, which is hard for convolution method to achieve. SpecificationThe most fundamental element of the filterbank reverberator structure is the decay line.Schroeder has made lots of efforts to create the artificial reverberation by using