What is a noise gate?

The short answer

A noise gate is an automatic on-off switch for a sound channel. You set a threshold, a loudness line drawn across the signal. When the incoming sound sits below that line, the gate is closed and the channel is muted. The moment the sound climbs above the line, the gate opens and lets everything through. Then, when you stop and the level falls back down, it closes again.

The whole point is the gaps. In the quiet moments between your words, all your microphone hears is room tone: the fan, the computer hum, the faint hiss of the room itself. A gate slams the channel shut during those gaps so that silence is actually silent. When you talk, your voice is loud enough to trip the gate open, so listeners hear you clearly, then hear nothing when you pause.

How a noise gate works

A gate watches the loudness of the incoming signal against your threshold and decides, moment to moment, whether to open or close. Four controls shape how it behaves, and they are worth knowing in plain terms because they are the difference between a gate that helps and one that chops your words.

• Threshold. The loudness line. Anything above it opens the gate; anything below it keeps the gate closed. Set it just above your room noise and just below your speaking level, so your voice reliably clears it and the room does not.
• Attack. How quickly the gate opens once you cross the threshold. Fast attack catches the very start of a word; too fast on a noisy signal can feel jumpy.
• Hold. How long the gate stays open after the sound dips, before it starts to close. A little hold keeps the gate from flickering shut in the tiny pauses inside a sentence.
• Release. How gradually the gate closes once hold runs out. A gentle release lets the tail of your voice fade naturally instead of getting cut off with a hard click.

Tune those four and the gate becomes invisible: it opens before you notice and closes into a clean silence you never think about. Get them wrong, and it either clips the front of every word or breathes open and shut on background noise.

Gate versus mute mic

People sometimes ask why they would use a gate when they could just mute the mic. The answer is that a mute button is a switch you flip by hand, and a gate is a switch that flips itself, hundreds of times a minute, based on whether you are talking.

When you mute manually you have to remember to do it, and you have to unmute before you speak, which is where the awkward half-second of talking-while-muted comes from. A gate needs no attention. It opens the instant your voice crosses the threshold and closes the instant you stop, so the channel is muted during every pause without you touching anything. Think of it as a mute button with perfect timing that never forgets.

Gate versus noise suppression

A gate is often confused with noise suppression, and the distinction is the single most useful thing to understand here. A gate only ever acts on the gaps. It judges loudness and nothing else, so when it is open, everything passes: your voice and the fan hum riding right along underneath it. A gate has no idea how to tell voice from noise, so while you talk, the background noise is still there.

Noise suppression works the other way. It listens for the difference between your voice and steady background noise and pulls the noise out continuously, even while you are speaking. It cleans under your voice, not just around it.

• A noise gate is a switch. It silences the gaps between words but does nothing about noise during them.
• Noise suppression is a filter. It removes the noise living underneath your voice, moment to moment.

They are partners, not rivals. The gate handles the pauses cheaply, and suppression handles the noise buried in the parts where you are actually talking. Run both and you get a clean room in the silence and a clean voice in the sound.

The noise gate in patchd

A gate lives naturally right at the input, before your voice travels anywhere else. In patchd, every channel has a free effects rack, and a noise gate is one of the effects in it, included on the Free tier, on every channel. You add it from the + Add Node menu and reorder it against the other effects by dragging, so you can put the gate early and let a clean, gap-silenced signal feed everything downstream.

Because the whole rack runs as real-time digital signal processing, the gate opens and closes live as you speak, adding about 10.7 ms through the bus at a 512 buffer, less at smaller ASIO buffers. The gated voice then leaves on a bus that other apps pick up as a microphone, so your call app, game, or stream software hears the version with the quiet gaps and never your raw room tone. Pair the gate with the rack's AI noise suppression and you cover both cases at once: the gate quiets the pauses, and suppression strips the noise from under your voice.

Setting a gate well

A gate rewards a light touch. Start by finding your threshold: with the mic live but you silent, note how loud the room is, then set the threshold just above that so the room stays shut out. Say a few words at your normal level to confirm your voice clears the line comfortably, with a little margin so a quiet aside still opens the gate.

Then soften the edges. Add a touch of hold so the gate does not snap shut in the natural micro-pauses inside a sentence, and a gentle release so the ends of your words fade instead of clicking off. If you find yourself raising the threshold higher and higher to kill background noise that bleeds through while you talk, stop, because that is not a gate's job. That noise belongs to reducing background noise on your mic, where suppression does the work a gate cannot. Let the gate do the one thing it is great at, silencing the gaps, and let the rest of the rack handle the rest.