A term that describes the interconnection of multiple components in an audio system, and the amount of gain increase or reduction that occurs at each point. A configuration with a good gain structure means that the components are working properly together to provide optimal gain with minimal distortion or noise.
(Also called Noise Gate) A type of expander that completely (or almost completely) attenuates a signal once it drops below a certain level, rather than simply reducing the level. (See also “Expander.”)
A term used to describe the number of times that the recorded audio signal has been copied.
The amount of clarity lost when recorded audio is copied, due to added noise and distortion.
(also called Golden Ratio) A ratio of height to width to length, where the width is approximately 1.6 times the height, and the length approximately 2.6 times the height. First calculated by the ancient Greeks, this ratio (known mathematically as “phi”) is used as an optimal ratio in many applications, including room dimensions and studio design (to achieve “optimal acoustics” in the room), and even in the design of certain acoustic instruments.
A type of equalizer that can adjust various frequencies of the incoming signal using sliders that are assigned to specific frequency bands. (See also “Equalizer.”)
An adapter that enables a three-prong power cord to plug into two-prong outlet. Some engineers wrongly use this plug to interrupt the ground connection and prevent buzz, but it is a VERY unsafe practice to break the ground connection using this plug without grounding the unit by another means.
A switch that breaks the connection between the ground point in one circuit and the ground point in another circuit, for the purpose of eliminating hum or buzz caused by ground loops.
A situation caused when one or more electronic devices are connected to the same ground at different points. The devices operate at different ground potentials, which creates voltage along the ground, resulting in a low-frequency hum that can be annoying at best and cause damage to gear at worst. The best resolution for ground loops is to ground all devices at the same point using a central power source. An alternative solution is to break the loop via ground lift switches or plugs, but this should be avoided when possible as it is considered an unsafe management of electricity.
In audio, group delay is a phenomenon within all electronic audio devices (e.g., speakers, amplifiers) in which different frequencies in the signal are output at slight delays from one another. In simpler terms, lower frequencies are delivered slightly more slowly than higher ones. In all devices, there is an inherent delay between input and output of the signal, but group delay specifically deals with the time delays between specific frequencies of the sound. The goal in any configuration is to keep the group delay as small as possible; in cases of extremely poor configurations, the delays between highs and lows can be audible.
An electric guitar (or device played like a guitar) that transmits MIDI data that can be used to control synthesizers and sound modules.
See “Effects Processor.”
(Also called Precedence Effect) Simply stated, a factor in human hearing in which we perceive the source of a sound by its timing rather than its sound level. In his research, Helmut Haas determined that the first sound waves to reach our ears help our brains determine where the sound is coming from, rather than its reflection or reproduction from another source. The reflection of the sound must be at least 10dB louder than the original source, or delayed by more than 30ms (where we can perceive it as an echo), before it affects our perception of the direction of the sound. This is what helps us distinguish the original sound source without being confused by reflections and reverberations off of nearby surfaces. Understanding the Haas effect is particularly useful in live audio settings, especially in large venues where loudspeakers are time-delayed to match the initial sound waves coming from the source.
A change in pitch equivalent to adjacent keys on a piano. Also known as a “semitone.”