Noise gate vs noise suppression

Search for a fix for mic noise and you will find both tools recommended interchangeably, as if they were two brands of the same thing. They are not. A noise gate and noise suppression attack different halves of the same problem, and the fastest way to see that is to run one noisy recording through each and compare what comes out.

Same input, two different outputs

Picture a typical noisy mic signal: your words, with a steady carpet of hiss underneath them, and that same carpet filling the gaps whenever you pause. Fan noise, computer hum, the room itself. Now process it twice.

Through the gate: the gaps go dead silent. The gate watches your level, and the moment it drops below a threshold you set, the channel mutes. But listen closely while you are talking and the hiss is still there, riding along under every word. The gate judges loudness and nothing else; while your voice holds it open, everything underneath your voice comes through too.

Through suppression: the hiss is gone everywhere, including under your words while you speak. Suppression separates voice from noise across the whole signal, not just the quiet parts. But it does nothing extra for the gaps: with the hiss stripped, your pauses carry faint residual room instead of the hard silence a gate delivers.

So the answer to "gate or suppression?" is usually "yes." Suppression strips the floor, the gate seals the gaps. Partners, not rivals, and in patchd both are free effects on every channel.

Where each one fails, and the knob that fixes it

Each tool has a characteristic failure mode, and each ships with a control built specifically to handle it.

• The gate chatters near the threshold. Trail off at the end of a sentence and your level hovers right at the line, flicking the gate open and shut like a bad relay. The fix is hysteresis (default 0 dB, up to 24): the gate opens at your threshold but refuses to close until you are that many dB quieter, so hovering between the two lines never flickers it.
• The gate clips the front of words. A gate is closed by definition when you start talking, so a slow attack shaves the first consonant off every sentence. Keep it fast: the default is 1 ms, and listeners forgive hiss long before they forgive missing consonants.
• Suppression can color your voice. Pushed hard, separating voice from noise starts to cost some of the voice: heavy settings can leave you sounding thin or processed. patchd's suppression ships with an honest Mix control instead of a single on switch, so you blend between the raw and fully cleaned signal and stop where the noise is gone but you still sound like yourself.

Notice the asymmetry: the gate's failures are timing problems, fixed with more nuanced timing rules. Suppression's failure is a quality tradeoff, fixed by dialing back how much of it you take. That difference is not an accident, and the advanced tier explains why.

A threshold versus an estimator

Under the hood, the two tools are different kinds of machine. The gate reduces your entire signal to one number and compares it to a line. That number is the envelope, a running estimate of your level that grabs peaks instantly and lets go of them slowly:

Every decision the gate makes is that envelope against a threshold, both converted to linear amplitude. With hysteresis in play there are two lines, one to open and a lower one to close:

That is the whole gate: a one-dimensional judgment, made thousands of times per second. It is why the gate is cheap, predictable, and utterly blind to what the sound is. A cough and a word look identical to an envelope follower; only their loudness differs.

Suppression is the opposite kind of machine. Instead of comparing one number to a line, it runs a trained model that continuously estimates which parts of the incoming signal are voice and which are noise, and rebuilds the signal with the noise scaled away. It never asks "is this loud enough?" It asks "how much of this is you?", everywhere, all the time, which is exactly why it can reach under your words where a loudness test cannot. The cost is that its mistakes are estimation errors, not timing errors, which is why its safety valve is a Mix blend rather than another millisecond knob.

The recipe: suppression first, then the gate

Because they are different machines, order matters, and the right order is suppression before the gate. Suppression drops your noise floor, say from -50 dB down to -70 dB, and the gate sees that cleaner floor. Its threshold can now sit far below your quietest speech with headroom to spare, instead of being wedged a few dB above the hiss where soft words get clipped. The default threshold of -45 dB that merely worked against a -50 dB floor becomes generously safe against a -70 dB one. The full ordering logic, with the worked example of how a misplaced compressor wedges a gate permanently open, lives in the effect chain order guide.

In patchd, both effects are free nodes in the rack on every channel: drop suppression in, set the Mix by ear, drag the gate in after it, and set the threshold against the live meter. Whatever the chain produces is what every destination hears, from your headphones to your stream. patchd is in development now. Join the waitlist and we will tell you the moment it is ready to install.