Noise gates on dialogue: when they help and when they wreck a take

A noise gate turns the signal down when it falls below a level you choose. That is the whole idea. Everything else, the four familiar controls, exists to make that turning down sound less like a switch.

The four controls

• Threshold: the level below which the gate closes. Set it between the noise floor and the quietest word you want to keep.
• Attack: how fast the gate opens. Too slow and consonants lose their front edge.
• Hold: how long the gate stays open after the signal drops. This is what stops it chattering between syllables.
• Release: how gradually it closes. Long releases hide the transition; short ones sound like a door.

Why hard gating fails on dialogue

Dialogue is not just words. Breaths, mouth sounds and the room around the actor carry the illusion that the scene happens somewhere. A gate set aggressively removes all of it, so every line arrives out of a vacuum and drops back into one. Cutting between gated and ungated material is instantly audible.

The professional habit is to gate gently or not at all, then fill the gaps with matching room tone recorded on set. Thirty seconds of tone at wrap saves hours of guesswork.

Better tools for the same problem

• Manual clip gain and fades, which give exact control over each transition.
• Spectral noise reduction for continuous hiss or air conditioning.
• A high pass filter to remove rumble before you decide anything else.
• Choosing the cleaner of two microphones rather than repairing the noisier one.

A workable starting point

If you do gate, start with the threshold about 6 dB above the noise floor, attack at 1 ms, hold at 100 ms, release at 200 ms, and a range of 6 to 10 dB rather than full mute. A gate that only ducks the noise instead of erasing it is far more forgiving.

Compare the treated file against the original in a player with per channel monitoring before committing, and always keep the untouched source.