Once the signal arrives at an input on a mixing console, this signal can be adjusted in many ways by the sound engineer. A signal can be equalized (e.g., by adjusting the bass or treble of the sound), compressed (to avoid unwanted signal peaks), or panned (that is sent to the left or right speakers). The signal may also be routed into an external effects processor, such as a reverb effect, which outputs a "wet" (effected) version of the signal, which is typically mixed in varying amounts with the "dry" (effect-free) signal. Many electronic effects units are used in sound reinforcement systems, including digital delay and reverb. Some concerts use pitch correction effects (e.g., AutoTune), which electronically correct any out-of-tune singing.