Delay is an audio effect where an audio signal is sent as an input signal and played back after a period of time. In this circumstance, the delayed vocal tracks can be used in several ways depending on the time of the delay and the intent of the effect. Delays can range from performing a subtle echo of the original audio signal, to making looped and repeating sounds eventually resulting in a decaying echo.
Delay effects were initially created using tape machines and tape loops in the 1940s and 1950s. This developed into analog effects units in the 1970s, which were able to specifically control either tape or solid state bucket brigade delay circuits within a housed environment. These eventually incorporated other audio effects (such as spring reverb) to expand the degree of creative control.
Digital delay effects units and pedals based off of algorithms were next to be invented, providing more precision for delay times and streamlining its involvement within the recording process. As recording software like Virtual Studio Technologies (VSTs) and Digital Audio Workstations (DAWs) became the predominant choice for recording studios and audio production, plug-ins were developed for use within these programs to simplify the process, stripping delays down to a more simplified set-time delay with usually few other sonic aesthetics included.
- A doubling echo creates a short-range delay to a recorded sound.
- Flanging, chorus and reverberation (link) are all delay-based sound effects. Flanging and chorus delay effects are usually short and modulated. Reverberation is made up of multiple, consecutive echoes and feedback which blurs the delays together
- Straight delay compensates for the movement of sound through the atmosphere. Unlike other types of audio delay, this is generally not mixed back in with the original signal