What is a noise gate and when might you use one in post?

• A. A processor that mutes or attenuates audio below a threshold; used to reduce room noise during pauses.
• B. A device that boosts the loudest frequencies to enhance presence.
• C. A compressor that reduces dynamic range during loud passages.
• D. A reverb unit that simulates room acoustics.

Answer: (B)

A noise gate mutes or attenuates audio that falls below a defined threshold. In post-production, you’d use it on dialogue tracks to clean up room noise, hum, or mic hiss during pauses, so the quiet moments don’t reveal unwanted background sound. The goal is to keep the spoken part intact while suppressing the low-level noise that unfolds when there’s no dialogue.

Think of the controls as shaping when the gate opens and closes: the threshold tells the gate what level counts as “silence,” the attack time decides how quickly the gate closes when the signal dips, and the release time determines how smoothly it opens back up as the dialogue returns. A hold control can prevent rapid on/off switching during short pauses. These settings help you avoid cutting off spoken syllables or letting noise leak through.

The other options describe different tools: boosting the loudest frequencies would be an enhancer or equalizer trying to add presence, a compressor reduces dynamic range rather than silencing quiet parts, and a reverb unit adds space. None of these perform the quiet-part suppression that a noise gate is designed for, which is why the gate’s function is distinct and valuable in post.