Automatic gain control (AGC) is audio processing that automatically raises or lowers a microphone's level so that quiet talkers, loud talkers, and people near or far from the mic all reach the far end at a similar volume. In a meeting room, it's what keeps the person at the end of the table from sounding faint while the person next to the mic doesn't blast everyone's speakers.
How AGC works
AGC continuously measures the level of the incoming speech and compares it with a target level.
- Measure: The processor tracks the average speech level over a short window.
- Compare: If speech is below target, it adds gain. If it's above, it reduces gain.
- Smooth: Changes are applied gradually (attack and release times) so the level doesn't pump up and down audibly.
- Limit: A maximum gain stops it from boosting background noise to full volume when nobody is talking.
Good AGC works with the other audio blocks, mainly acoustic echo cancellation and noise suppression. Gain is usually applied after echo cancellation, so AGC doesn't amplify echo before it has been removed.
Why it matters in meeting rooms
- Distance varies. People sit 3 ft from the mic and 15 ft from the mic in the same room. Level drops quickly with distance.
- Voices vary. Some people project, some mumble.
- Remote listeners have no control. They can only change their overall volume, not one talker's level.
Without AGC, remote participants keep reaching for the volume. With too much AGC, room noise surges up during pauses and voices sound compressed.
AGC in meeting platforms
Teams, Zoom and Google Meet apply their own processing to microphone audio, and many devices also run processing on board. Certified room devices are tuned to work with the platform's processing, which is one reason to choose certified gear. See Teams Rooms certified devices and Zoom Rooms certified hardware.
If you use an external DSP in a large room, decide where AGC runs. Running aggressive AGC in both the DSP and the software can cause pumping. Typically the DSP handles it and the software's "auto adjust" is left at the platform default.
AGC isn't a substitute for mic coverage
AGC can lift a distant voice, but it lifts room noise and reverberation along with it. A voice 20 ft from the mic in a reverberant room will still sound hollow after AGC. If people at the far end of the table sound distant, the fix is more microphones closer to them, not more gain. See mic pickup range and daisy-chain conference microphones.
What to look for when buying
| Feature | Why it matters |
|---|---|
| AGC listed in audio processing | Confirms the device levels speech on its own |
| Echo cancellation and noise suppression | AGC needs these to avoid boosting echo and noise |
| Adjustable or defeatable AGC (DSPs) | Needed when integrating with other processing |
| Platform certification | Confirms tuning with Teams or Zoom processing |
| Expansion mics | Better coverage reduces how hard AGC has to work |
Catalog products that list AGC
Manufacturers don't always list AGC separately, even when their audio processing includes level control. In our catalog, the Yealink CP50 daisy-chainable mic/speaker explicitly lists automatic gain along with noise and echo cancellation, de-reverberation and full-duplex audio.
For other devices, check the manufacturer's spec sheet or the product's guide page. Related: best speakerphones and best microphones for Teams and Zoom.
Remote attendees complaining about uneven volume? Describe the room and your current setup and we'll suggest where to add mics.
Related guides
- What Is RT60? Reverberation Time in Meeting Rooms
- How to Improve Audio in a Large Conference Room
- Meeting Room Audio Recording: Mics and Recorders
- Conference room microphones: types and how to choose
- What Is a Table Microphone for Conference Rooms?
- Best Conference Room Audio and Sound Systems by Room Size
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