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Chapter 2: What Is A Gate?
DN530
6 Operator Manual
Typical creative uses
The human ear is connected to an extremely sophisticated organ for processing
incoming audio information — the brain. Even in situations where there are many
sound sources, we seem to be able to tune in to the sounds we want to hear and reject
others. This is sometimes known as the cocktail party effect, where it is possible to pick
out one person’s voice — even at a distance — from may conflicting conversations.
The microphone (mic) is less selective in its pick up, being sensitive to all sounds within
its range and coverage angle. For example, a mic set to pick up the snare drum of a
drum kit will pick up every other drum and cymbal to some extent, and probably the
bass guitarist as well. When several mics are positioned on the kit, each one giving a
good sound on its own particular drum, but they will all pick up unwanted instruments
as well, making the sound less clear.
One solution is to use a noise gate on each mic (see diagram below). The gate will
reduce the output from the mic to almost zero when the drum is silent, yet will open
practically instantaneously when the drum is played. As the sound from the drum
decays, the gate will close again and reject noise from the rest of the kit.
The threshold level represents the sound level at which the gate will open. Any sound
exceeding the threshold triggers the gate. Sounds at lower levels leave the gate closed
and the mic will be almost completely silent.
Time
Threshold level
Signal level
Gate closed
Snare
Background noise
Gate closedGate closed
OpenOpen
Output signal
Signal without gating
Signal with gating
Range (attenuation
depth)