Noise Gate Simulator

Noise Gates Explained: How to Silence Unwanted Noise in Your Recordings

A typical home studio recording has a noise floor of -50 to -60 dBFS from computer fans, air conditioning, room ambience, and microphone self-noise. A noise gate silences audio that falls below a threshold you set, removing that background noise during pauses between phrases, hits, or vocal lines. This tool processes your audio file sample by sample in JavaScript, applying a full gate envelope with attack, hold, release, and range controls. The result is a cleaner recording you can export as WAV without installing any software.

What Is a Noise Gate?

A noise gate is a dynamics processor that attenuates audio below a defined threshold. Think of it as a door that opens when the signal is loud enough and closes when it is not. When the input signal exceeds the threshold, the gate opens and audio passes through at full volume. When the signal drops below the threshold, the gate closes after a hold period and attenuates the audio by the range amount. At -80 dB range, the closed gate produces near-silence. At -20 dB range, the closed gate reduces the signal by 20 dB, which is a gentler reduction that preserves some room tone.

Gates are used on virtually every drum kit recording to silence the microphones between hits. A tom mic picks up the snare bleed and cymbal wash constantly, but you only want it active when the tom is actually being hit. A gate set to open on the tom's attack and close during the decay removes the bleed entirely. The same principle applies to guitar amp recordings (removing hum between phrases), vocal tracks (removing breath noise and room ambience between lines), and podcast recordings (removing keyboard typing and chair creaks).

Understanding Gate Parameters

Threshold is the level (in dBFS) at which the gate decides to open or close. Set it just above your noise floor. If your noise floor is -55 dBFS, a threshold of -45 to -50 dBFS will open the gate on actual signal but keep it closed on background noise. Setting the threshold too high cuts off the quiet parts of your performance. Setting it too low means the gate never closes and the noise passes through.

Attack is how fast the gate opens when the signal exceeds the threshold. A fast attack (1-5 ms) is needed for drums and percussion, where the transient is the most important part of the sound. A slow attack (10-50 ms) can be used for sustained instruments where a gradual open is less noticeable. At 0 ms, the gate opens instantly, which can produce a click if the signal starts abruptly.

Hold is how long the gate stays open after the signal drops below the threshold. This prevents the gate from fluttering (rapidly opening and closing) when the signal hovers near the threshold. A hold of 50-200 ms is typical for vocals. For drums, 20-50 ms is usually enough. Without hold, a sustained note that dips momentarily will cause the gate to close and reopen, producing an audible chop.

Release is how fast the gate closes after the hold period expires. A fast release (10-50 ms) produces an abrupt cutoff, which is fine for drums but unnatural for vocals and sustained instruments. A slow release (100-500 ms) fades the signal out gradually, which sounds more natural on vocals and acoustic instruments. Too slow a release on drums lets the bleed fade in after the hit decays.

Range (sometimes called depth) is how much the gate attenuates when closed. -80 dB is effectively full silence. -20 dB is a gentle reduction that preserves some room tone, which can sound more natural than complete silence. Partial range gates are useful when you want to reduce noise without making the pauses sound unnatural.

How This Tool Processes Audio

The gate operates on the raw Float32Array sample data from the decoded AudioBuffer. For each sample, it computes a short RMS (root mean square) amplitude over a 5 ms window. RMS is used instead of peak detection because it tracks the perceived loudness of the signal more smoothly, reducing false triggers from brief transient spikes that are not actually part of the performance.

When the RMS exceeds the threshold, the gate enters the attack phase, ramping the gain from the closed value (range) to 1.0 (fully open) over the attack time. The hold counter resets. When the RMS drops below the threshold, the hold counter starts counting down. Once hold expires, the gate enters the release phase, ramping the gain from 1.0 back to the range value over the release time. Each sample is multiplied by the current gain value and written to the output buffer. This is the same algorithm used by hardware gate processors and DAW gate plugins, implemented in JavaScript.

Noise Gate vs Noise Reduction

A noise gate is a binary processor: the signal is either at full volume or attenuated by the range amount. It does not adapt to the frequency content of the noise. Noise reduction (like iZotope RX, Waves NS1, or Audacity's Noise Reduction) analyzes the noise spectrum and removes those specific frequencies from the signal continuously, even while the desired audio is playing. Noise reduction is more sophisticated but can introduce artifacts (watery, underwater sounds) if overapplied.

Use a gate when your noise is consistent and your signal has clear pauses (drums, spaced vocal phrases, guitar parts with rests). Use noise reduction when the noise is constant and overlaps with the signal throughout (hiss on an old tape recording, air conditioning during a continuous vocal performance). For measuring the noise floor of your recording before setting a gate threshold, the Decibel Meter provides real-time level readings.

Using the Noise Gate with Other Tools

After gating, you may want to apply fades to smooth the gate's transitions. The Fade In / Fade Out Tool can add a short fade at the start and end of the gated file. If you need to trim the file to isolate a specific section before gating, use the Audio Trimmer. For recording new audio to process, the Audio Recorder captures microphone input directly in the browser. And for checking the final loudness of your gated and processed file, the LUFS Loudness Meter measures integrated loudness and true peak against streaming platform targets.

For technical reference on noise gate design and dynamics processing, the AES17 standard on digital audio engineering defines measurement methods for dynamic range and noise, and the Web Audio API specification on dynamics processing documents the browser-native DynamicsCompressorNode, which shares the same envelope-following principles used by this tool's gate implementation.