Click here to purchase the entire book in PDF format. History Since the application of digital signal processing to audio signals, there have been many attempts to create an impression of space using various algorithms. For the past 40 years, numerous researchers and commercial developers have devised multiple strategies for synthesizing virtual acoustic environments with varying degrees of success. Different methods have proven to be more suited to particular applications which can be divided into two major fields: commercial classical music production and film and television post-production commercial pop music production, electroacoustic music composition (including computer music) and computer games. In the former case, synthetic reverberation is typically used to mimic real acoustic environments, generally with the intention of deceiving listeners into believing it is an actual space. In the latter case, the synthetic environments are generally intended to appear to be exactly that - synthetic - acoustics which are physically impossible in the real world, essentially resulting in the processing being used more as an instrument than an environment. In either instance, the reverberation must be aesthetically acceptable in order to enhance and complement rather than detract from the performance it accompanies. Unfortunately, as is pointed out by Gardner [Gardner, 1992a], since a large part of the development of synthetic reverberation algorithms has been carried out by corporate concerns for commercial products, many secrets regarding their algorithms are not shared. Companies that rely on the sale of such products maintain superior product quality by ensuring that their procedures are not used by competitors, thus knowledge is hoarded rather than distributed, consequently slowing progress in the field. As a result, many specifics regarding current commercially-developed algorithms can only be either surmised or reverse-engineered. Various algorithms and approaches to acoustics simulation have been developed since the advent of digital signal processing in the audio and film industries. These can be loosely organized into three groups based on their basic procedural characteristics: tapped recirculating delay models geometric models and stochastic models.