Ambience – Background noise added to a musical recording to give the impression that it was recorded live. Often done using short room reverbs.
Decay – How fast a sound fades from a certain loudness.
Delay (or echo) – A processor that creates copies of a sound source that repeat over and over, fading slowly. Commonly used with vocals and electric guitar.
Feedback – When a signal is sent through an amplifier and into a microphone, which picks up the sound and sends it back through the amplifier, and so on. The loop of sound creates high pitched whines. Also refers to the parameter on a delay that adds more repetitions of the sound.
Ping-Pong – A delay that alternates between the left and right speakers.
Predelay – A short delay between a sound and when an effect begins. Usually measured in milliseconds (ms). For example, a 50ms reverb pre-delay means that there is 50ms between the actual sound and when the reverberated sound starts.
Slapback – A quick delay (30-200ms) with little to no repetitions.