Audio ducking in OBS for webcam speech

What audio ducking in OBS does

Audio ducking in OBS Studio automatically lowers other sound—music, game audio, alerts, or desktop playback—when you speak, so the voice from your webcam microphone (or a separate mic used with a webcam) stays intelligible. The usual method is a Compressor filter on the source you want to quiet, with your microphone set as the sidechain, or ducking, source. When that mic signal rises above the compressor threshold, OBS reduces the other source; when you stop talking, the other source returns. This is a documented filter behaviour in OBS, not a separate “ducking” app. How well it works depends on a correctly selected input, a threshold that matches your speaking level, and how noisy the webcam mic is. Built-in webcam microphones often pick up keyboard, fan, and room sound, which can trigger ducking when you are not speaking or fail to trigger it when you are.

Set ducking with a sidechain compressor

Apply the compressor to the audio you want to duck, not to the webcam mic itself. Typical targets are Desktop Audio, a music or media source, or an application capture. Open that source’s filters, add a Compressor, and choose your webcam or speech input in the Sidechain/Ducking Source control. OBS then uses the mic only as a detector: the mic still records on its own track, while the compressor turns the other track down when you talk.

Use the compressor’s threshold so normal speech crosses it and quiet room noise does not. Ratio controls how strongly the other audio is reduced once the threshold is crossed; a higher ratio ducks more aggressively. Attack is how quickly the other audio drops after you start speaking; release is how long it takes to come back after you stop. Exact numbers are not supplied here because useful values depend on mic level, room noise, and how loud the ducked source is. Start with a moderate ratio, a short attack so speech is not buried at the start of a sentence, and a release long enough that the music does not pump between words. If evidence for a specific webcam’s output level is missing, treat any published “default” numbers as starting points only and adjust by listening.

Choose the right webcam audio input

Ducking only follows the source you assign as the sidechain. In OBS, confirm that the device listed for the mic—and in the compressor’s sidechain list—is the webcam’s microphone (or the external mic you actually speak into), not a loopback, HDMI capture, or unused headset. Many webcams appear as a combined video-and-audio device in the operating system; OBS Audio Input Capture or the global Mic/Aux device must point at that same device. If the webcam is muted in the OS, exclusive to another app, or set as a different default than OBS is using, the compressor will not see speech and will not duck.

For conferencing or streaming, keep speech on its own OBS track when you can. That lets you duck music or game audio without compressing the voice, and it keeps the webcam mic available as a clean sidechain. Mixing voice and music on one track before the compressor makes ducking harder to control and can squash the voice along with the bed.

Webcam mics and speech quality

A built-in webcam microphone is usually a small omnidirectional capsule at the camera, not at the mouth. Compared with a dedicated headset or desktop mic, it typically sits farther from the speaker, captures more room reverberation, and has a narrower usable dynamic range. Those traits affect ducking: the speech peak may sit only a little above keyboard and HVAC noise, so a threshold that catches your voice may also duck on typing, and a threshold that ignores typing may miss soft speech.

• Sit closer to the camera or raise speaking level so voice is clearly louder than the room before you set the compressor threshold.
• Add a Noise Gate or expander on the webcam mic (on the mic source, not on the ducked music) so low-level noise does not open the sidechain. A gate is a documented OBS filter; it does not replace a quiet room.
• Keep the webcam mic out of Advanced Audio Properties monitoring loops that feed the same signal back into the sidechain.
• If the webcam offers only one analog-looking input with no documented polar pattern or sensitivity, do not assume it will duck as reliably as a close headset mic; that comparison is an inference from typical webcam placement, not a measured spec for a named model.

Conferencing, streaming, and compatibility

OBS ducking applies inside OBS: it changes what OBS mixes and what you send from OBS (virtual camera plus audio, a stream, or a recording). It does not change how Zoom, Teams, or a browser meeting app processes the webcam’s raw microphone unless those apps are receiving the OBS mix, for example through a virtual audio cable or OBS’s monitoring output. If the meeting app is capturing the webcam mic directly, OBS compressor settings will not duck that app’s playback. Match the capture path to the goal: duck inside OBS when OBS is the mixer; use the meeting app’s own noise or music controls when the webcam is selected there as a native mic.

Sample rate and channel count should match across the webcam input, OBS, and the output. A mismatch can cause crackle or a delayed sidechain, which makes ducking late or choppy. Prefer the device’s native rate in OBS audio settings rather than undocumented resampling tricks. Stereo webcam mics are often two similar capsules; ducking still keys off overall level, so a stereo webcam does not by itself give directional speech isolation.

How to tell if ducking is working

Watch the ducked source’s meter in OBS while you speak into the webcam. The music or desktop meter should fall when you talk and recover after you stop, while the mic meter should still show your voice. If music ducks when you are silent, the sidechain is hearing noise or the threshold is too high in the wrong direction (too sensitive). If music never ducks, the compressor is on the wrong source, the sidechain is the wrong device, the mic is muted, or the threshold is set so only louder peaks than your webcam produces will trigger it.

Listen for pumping (music volume bouncing on every syllable), buried first words (attack too slow), and a hole after you finish a sentence (release too slow or threshold too sensitive). Those are mixing artefacts, not a sign that OBS lacks ducking. There is no supplied lab measurement here for how many decibels a given webcam will pull the compressor; judge by meters and a short test recording of speech over a constant music bed.

Limits and when to change the mic

Ducking cannot make a noisy webcam sound like a close vocal mic. It only turns competing programme audio down. If the webcam already distorts, if the OS AGC (automatic gain) is pumping the webcam on its own, or if two apps open the same webcam mic exclusively, OBS may see an unstable level and duck erratically. In those cases the next action is to pick one capture owner, disable extra OS enhancements if they fight OBS, or use a dedicated speech mic while keeping the webcam for video. Model-specific frequency response, self-noise, and max SPL for unnamed webcams are not documented in this brief; treat those as unknown and evaluate by a test take rather than by assumed specs.

If you need a supported next step: confirm the webcam mic is the selected OBS input and the compressor sidechain; put the compressor on music or desktop audio; set threshold from your actual speech versus room noise; gate the mic if noise false-triggers ducking; then record a short clip with speech over a bed. If the bed still fights the voice after that, the constraint is the webcam’s distance and noise, and a closer speech mic is the practical upgrade—not a different ducking toggle.