Reverb

Reverb, short for reverberation, is the persistence of sound after the original source stops, due to the superposition of many delayed reflections from surfaces in an environment. When sound is produced, it travels and reflects off walls, ceilings, floors and objects. The reflections combine with the direct sound and with each other to create a decaying tail that gives a sense of space. The rate of decay and the tonal quality depend on room size, shape, surface materials and diffusion. The reverberant effect is commonly summarized by the reverberation time RT60, the time required for the sound to fall by 60 decibels.

Natural reverb occurs in real spaces; artificial reverb refers to electronic or digital systems that reproduce this phenomenon. In audio work, reverb can be recorded from acoustic spaces or synthesized digitally. Two broad approaches are used: convolution reverb, which uses an impulse response measured from a real space or hardware unit to apply a faithful reverberation; and algorithmic reverb, which simulates reverberation using mathematical algorithms, providing adjustable density, diffusion and decay without a fixed impulse response.

Common historical types include plate reverbs (metal plate mechanically vibrated to create a tail), spring reverbs (a transducer driving a metal spring, popular in guitar amps), and chamber reverbs (sound through a separate room). Digital reverb also emulates room or hall types. In contemporary music and broadcasting, reverb is used to create cohesion and sense of space, or to intelligibility depending on settings.

Measurement involves impulse response and RT60; design considerations include early reflections, tail length, diffusion and pre-delay. In acoustics, appropriate reverb is part of room design, while in production it is a tool requiring careful mixing to preserve clarity.