What Is a Noise Gate?

A noise gate is an audio processor, either hardware or a plugin, that acts as an automatic volume control. It silences or reduces the level of any signal that falls below a user-defined threshold, effectively "closing the gate" on background noise when the main sound source is inactive. When the signal exceeds the threshold, the gate "opens" and lets the desired audio pass through. In vocal recordings, a noise gate can remove breath pops, room rumble, electrical hum, and other low-level noises that occur between phrases or during silence, leaving only the clean vocal performance.

Noise gates are distinct from other noise reduction tools like expanders or spectral editors because they operate on amplitude alone, not frequency content. This makes them simple yet powerful for situations where the noise floor is significantly lower than the vocal level. For more complex noise profiles (e.g., constant fan noise or hiss that overlaps with the vocal), additional processing like a noise gate combined with an expander or a dedicated noise reduction plugin may be necessary. Understanding this distinction is key to using gates effectively.

Key Parameters of a Noise Gate

To use a noise gate properly, you must understand its core controls. Most gates offer these adjustable parameters:

Threshold

The threshold sets the level (in dB) at which the gate opens. Any signal above this level passes through; any signal below is attenuated or muted. Setting the threshold correctly is the single most important step. If it’s too high, the gate will shut off parts of the vocal. If it’s too low, the gate won’t close and noise will persist. A good starting point is to place the threshold just above the noise floor—the level of background noise present when no one is singing.

Attack

Attack controls how quickly the gate opens once the signal crosses the threshold. Fast attack times (under 1 ms) are typically best for vocals to capture the initial transient of a word or syllable without a delayed fade-in. However, an extremely fast attack can cause a click or pop if the waveform has a sharp rise. In most digital plugins, a setting of 0.5 to 2 ms works well. For soft, breathy vocals, a slightly slower attack (3-5 ms) can make the gate sound more natural.

Hold

Hold determines how long the gate stays open after the signal drops below the threshold. This prevents the gate from rapidly opening and closing during short pauses or consonants. A hold time of 50-200 ms is common for vocals; too little creates a stuttering effect, while too much lets noise through during longer pauses. Adjust hold based on the natural rhythm of the performance.

Release

Release controls how long the gate takes to close after the signal falls below the threshold (and after the hold time expires). A release that is too fast will cut off the tail of a word abruptly, sounding unnatural. A release that is too slow will let noise fade in gradually, defeating the purpose. For vocals, a release of 100-500 ms is typical, but slower for ballads and faster for aggressive rap or rock. Listen for “breath cut-off” and adjust accordingly.

Range

Range (also called depth or reduction) sets how much the gate reduces the signal when closed. A range of -∞ dB completely mutes the noise, but this can sometimes sound too abrupt if the noise floor is high. Using a range of -20 to -40 dB can be more transparent, allowing a minimal noise floor to remain while still cleaning the track. Many engineers prefer a limited range to avoid an unnatural silence between phrases.

Step-by-Step Guide to Setting Up a Noise Gate on Vocals

Follow this workflow to apply a noise gate to a single vocal track in your DAW:

  1. Insert the noise gate on the vocal track as the first plugin in the signal chain (before compression or EQ). This ensures the gate works on the raw signal.
  2. Play a quiet section of the recording where no vocals are present. Note the level (in dB) of the background noise (the noise floor).
  3. Set the threshold about 3-6 dB above the noise floor. Start conservative; you can lower it later if needed.
  4. Set attack to around 1-2 ms, hold to 50 ms, and release to 200 ms as a starting point.
  5. Play the vocal and listen for the gate opening. If the gate clips the beginning of words, lower the threshold slightly or slow the attack. If the gate doesn’t close between phrases, lower the threshold or increase the range.
  6. Fine-tune release and hold by focusing on the ends of phrases. Adjust release to avoid cutting off the natural decay of the voice or letting noise seep in before the next phrase.
  7. Apply a gentle gain reduction using range, rather than full muting, for a more natural sound. A range of -20 dB to -40 dB is often sufficient.
  8. Bypass and compare to ensure the gate is only removing noise, not harming the vocal quality.

If your noise gate has a lookahead feature, enable it with a small value (1–5 ms). Lookahead allows the gate to anticipate the onset of the vocal and open slightly earlier, eliminating any latency-induced clipping.

Advanced Noise Gate Techniques

Sidechain Gating

Sidechain gating uses an external signal to trigger the gate. For example, you can set a gate on a background vocal track to open only when the lead vocal is present, preventing clashes. Or use a gate on a room microphone that opens when the singer’s voice hits a threshold, reducing ambience during silence. To set this up, route the key input (e.g., lead vocal) to the sidechain of the gate on the target track. Adjust threshold and attack as usual, but the gate now responds to a different signal source.

Gating Multiple Tracks with One Trigger

When recording a vocal group or double-tracking, you can use one noise gate on a bus or group channel, triggered by all vocal signals. This ensures uniform noise reduction across takes and prevents instances where one track’s gate opens while another’s remains closed, creating an odd shifting noise floor.

Using a Noise Gate as a Creative Effect

Beyond cleanup, noise gates can create rhythmic effects. By setting an extremely fast attack and release, and a high threshold, you can chop a sustained vocal into a stutter effect reminiscent of a gated reverb. Some plugins allow you to draw in gate patterns or sync to tempo. This is more common in electronic music but can add texture to pop and rock recordings.

Combining with an Expander

An expander is a gentler version of a noise gate; instead of opening/closing abruptly, it applies a variable gain reduction below the threshold (e.g., a ratio of 1:2 or 1:3). Using an expander before a gate can smooth out the effect, reducing noise gradually and letting the gate only handle the lowest level noise. Many modern plugins combine these into a single “noise gate/expander” module.

Common Mistakes and How to Avoid Them

  • Setting the threshold too high: this cuts off the tail of words, especially soft endings like “s” or “t”. Solution: start low and raise the threshold incrementally until the noise just vanishes, then back off a dB or two.
  • Using too fast a release: creates a chop-chop sound at the ends of phrases. Listen for unnatural breathing artifacts. Slow the release until the vocal decays naturally.
  • Relying on a gate alone: a noise gate cannot fix issues like air conditioning rumble that persists during singing. It only addresses noise when the vocal is silent. For constant background noise, use a noise reduction plugin (e.g., iZotope RX, Waves WNS) before the gate, or treat the recording environment. For more on noise reduction strategies, see Sound on Sound’s guide to cleaning up location recordings.
  • Forgetting to pre-contextualize the gate in the mix: a gate that sounds fine in solo may reveal odd pumping when other instruments play. Always audition the gate in the full mix.
  • Using a gate on every track by default: sometimes the natural room tone or breath sounds contribute to the performance’s vibe. Overgating can make a recording feel sterile. Only apply a gate if the noise is genuinely problematic.

When to Consider Alternatives to a Noise Gate

Noise gates are most effective when the desired signal (vocals) is significantly louder than the noise floor. If the noise is broadband (like computer fan hiss) or occurs simultaneously with the singing (like vocal sibilance mixed with hiss), a gate alone will not help. In those cases, try these approaches:

  • Noise reduction plugins that learn a noise profile and subtract it from the entire track (e.g., iZotope RX). These can remove constant noise without affecting the vocal.
  • Expansion: a gentle expander (ratio 1:1.5 to 1:3) can reduce noise without hard gating.
  • Manual editing: for short sections of noise, simply cutting the waveform or fading can be more precise than a gate.
  • Gated reverb: if you want to add ambience selectively, use a gate on a reverb return rather than on the dry vocal.

For a comprehensive overview of audio gating principles, the Wikipedia article on noise gates offers a solid technical foundation.

Many DAWs include a built-in noise gate. For more control, consider third-party options:

  • FabFilter Pro-G: offers versatile modes (including a classic gate, expander, and upward expander), lookahead, and dry/wet mix.
  • Waves NS1 & WNS: specialized noise suppression plugins that combine gating with spectral analysis. Useful for dialogue and vocals.
  • Klevgrand Brusfri: a simple noise gate with a learn function that automatically sets the threshold based on the noise floor.
  • Hardware units: classic analog gates like the dbx 1074 or Drawmer DS201 are still used in studios for tracking and live sound. They offer immediate, tactile control.

For a detailed comparison of plugin vs hardware gating, check Recording Revolution’s article on the topic.

Final Thoughts on Cleaning Vocals with Noise Gates

Mastering the noise gate is an essential skill for any audio engineer working with vocals. When applied correctly, it removes extraneous noise without compromising the performance’s dynamics and emotion. The key lies in careful threshold and release adjustments, combined with an understanding of when gating is appropriate and when to use other tools. By following the steps outlined here and listening critically, you can transform a noisy vocal track into a clean, professional-sounding recording that sits perfectly in a mix.

Remember: no noise gate is a substitute for a good recording environment. Treat your room, use a proper microphone technique, and minimize background noise at the source. Then let the gate handle the rest. With practice, you’ll develop an ear for the subtle adjustments that make all the difference between a gated sound and a natural, polished vocal.