Time and Dynamic Based Effects

Time-Based Effect

A processor that manipulates time in some fashion, including effects like delay, echo, flanging, chorus, and reverbs.

Reverb

The sound left ringing in a room after the direct sound from the source is silenced, differing from echo as it is a wash of reflections without discrete echoes.

Hall

A type of reverb intended to re-create the ambience of a hall.

Plate

One of the first types of mechanical reverbs developed for recording studios, using a steel plate to create a wash of sound.

Room

A type of reverb that attempts to re-create the ambience of a small to medium-sized physical space.

Spring

A simple type of mechanical reverb developed by the Hammond Organ company, using physical springs to create the reverberated effect.

Chamber

A type of reverb created in a physical space by sending the dry source signal into a speaker enclosure located in an acoustically treated ambient space.

Delay

A discrete repeat of a signal at some period time after the original signal is played.

Echo

A delayed duplicate of the original signal heard at some time after the direct sound, having two to infinite repeats.

Chorus

An audio effect created by processing a signal through a number of short modulated delays, mixing the delayed versions with the original dry signal.

Flanging/Flanger

An effect created in the 1960s using two analog reel-to-reel tape decks playing back the same audio slightly out of sync.

Decay Time

The time it takes for the reverb in a room to stop ringing.

RT60

Abbreviation for Reverb Time-60 dB. The time it takes for the reverberation in a room to drop in level by 60 decibels.

Early reflections

In acoustics, the first reflections to be heard after the direct sound from a source.

Ambience

1. Sense of space. 2. The acoustical character of a space.

Pre-delay

A parameter in reverb units that sets the length of time between the initial source signal and the appearance of reverb.

Phase Shifter

An audio effects processor that mixes together a dry signal and a slightly delayed version of that signal to create audible phase cancellations.

Diffusion

In reverbs(hardware/software), a parameter that sets how dense or 'thick' the reverb effect sounds.

Comb Filtering

A type of cancellation or filtering effect that causes a series of deep notches and peaks in frequency response, usually due to phase differences between sound waves.

Tape Delay

Originally, an echo effect created using a reel-to-reel tape recorder.

Equalizer (EQ)

An audio processor that boosts or cuts the level of a particular frequency or range of frequencies.

Equalizer

Originally developed by the telephone company to enhance the audio quality of phone lines.

Compressor

A device or plug-in that reduces the dynamic range of a signal. A threshold level is set. When a signal level rises above the threshold, the signal level or gain is reduced by an amount defined by a ratio setting.

Ratio

Determines how much the output signal is allowed to rise in level versus the input level. For example, a 2:1 ratio would allow the output to increase by one decibel for every two decibels the input level increases.

Attack

Determines how fast the compressor operates on a signal after it has crossed the threshold.

Release

Determines how fast the compressor lets go of the signal after it drops back below the threshold.

Limiter

A compressor with a very high ratio—10:1 or even higher—resulting in very little change in output level no matter how much the level of the input signal changes.

Gate (Noise Gate)

A type of dynamics processor that automatically shuts off a channel when no desired signal is present so that any noise floor is muted.

Threshold (Gate)

Determines the minimum signal level that will open the gate—signals higher than the threshold will open the gate, and audio will pass as normal.

De-Esser

A dynamics processor that is set up to respond to high frequencies in order to reduce the levels of sibilants in a signal.

Expander

The opposite of a compressor. An expander is used to increase the dynamic range of a signal.

Compander

Compression/expansion. A noise-reduction technique in which the input signal is compressed before it is recorded or processed, and then expanded on playback or output.

Threshold (Compressor)

Defines the point where the compressor starts to work. Compression takes place when the signal peaks over the threshold.

Hold Parameter

Keeps the gate open for a specific amount of time.

Sibilants

High-frequency sounds such as 's', soft 'c', and other similar sounds that may require control to reduce distortion.

Dynamic Range

The difference between the quietest and loudest parts of a signal.

Noise Floor

The level of background noise in a signal.

Signal Level

The strength of an audio signal, typically measured in decibels (dB).

Decibel (dB)

A unit used to measure the intensity of a sound or the power level of an electrical signal.

Output Signal

The processed audio signal that comes out of a device after being modified by effects like compression or limiting.

Input Signal

The original audio signal that is fed into a device for processing.

Dynamic Processor

A device or software that modifies the dynamic range of an audio signal.

Audio Input

The point at which audio signals enter a device for processing.

Threshold

The input level at which the gate opens, allowing desired signals above the threshold to pass while gating background noise below it.

2:1 Ratio

A ratio where a 2-dB change in input level results in a 1-dB change in output level, reducing the output signal level by 50%.

4:1 Ratio

A ratio where a 2-dB change in input level results in a 0.5-dB change in output level, reducing the output signal level by 75%.

Attack Time

Defines how fast a compressor starts to reduce gain when the signal exceeds the threshold value, commonly set in milliseconds.

Auto-release function

A feature in some compressors that adjusts the release time based on the input signal, useful for compressing material with unpredictable patterns.

Make Up Gain

Gain available to amplify the signal at the final output stage of a device, compensating for peak volume reduced when compression or limiting is applied.

Gain Reduction

The attenuation of a signal's peak levels using a compressor or limiter.

Sibilance

High-frequency vocal sounds, such as ss and sh, that live in the 5- to 10-kHz range, often controlled by a de-esser.

Key Input / Side Chain

An audio input used to trigger a compressor or noise gate's operation, which is not audible through the device but tells it to process or open.

Ducking

A common use of a sidechain to reduce the level of background music when a voiceover comes in.

Knee

The point in a dynamics processor where a change in response takes place, indicating where compression begins.

Hard Knee

The mode of operation of most compressors that immediately starts attenuating the signal according to the ratio as soon as the signal crosses the threshold.

Soft Knee

A feature of some compressors that gently begins to introduce compression as the signal approaches the threshold, differing from hard-knee compression.