If your Microsoft Teams or Zoom room has an echo, the room system itself is rarely the culprit. In commercial AV work the cause is almost always one of six things — and five of them cost nothing to fix.
1. Somebody in the room also joined on their laptop
This is the most common cause by a wide margin. When a person sitting in the room joins the same meeting on their laptop without muting it, their laptop microphone picks up the room speakers and sends that audio back into the call. Remote participants then hear themselves a fraction of a second late, which is exactly what echo sounds like.
The fix: everyone in the room joins with their own audio off, and the room system is the only audio device in use. Both Teams Rooms and Zoom Rooms support proximity join with device audio muted automatically — worth switching on rather than relying on people to remember.
2. Echo cancellation has nothing stable to lock onto
Every conferencing platform runs acoustic echo cancellation (AEC), which works by subtracting the speaker output from the microphone input. To do that it needs a predictable, fixed delay between the two. If your microphone and speaker sit on separate unsynchronised devices — a USB microphone plus display audio over HDMI, say — AEC cannot model that delay reliably and echo leaks through.
The fix: keep the microphone and speaker inside the same audio device chain. A certified room system, or a DSP handling both, gives AEC the reference signal it needs.
3. The microphone is too close to the speaker
Ceiling speakers directly above a table microphone, or a soundbar sitting inches from a boundary microphone, will defeat even good echo cancellation. The microphone receives the speaker output at a level comparable to the person talking, and no amount of processing separates them cleanly.
The fix: keep direct paths between speaker and microphone as long and as off-axis as the room allows. In practice this usually means speakers toward the display wall, microphones over the seating.
4. The room is too reflective
A glass-walled meeting room with a hard table and no soft surfaces has a long reverberation time. Reflections arrive at the microphone tens of milliseconds after the direct sound, and AEC treats late reflections as new audio rather than echo to be cancelled.
The fix is acoustic, not electronic: soft ceiling tiles, carpet, curtains or a few absorption panels on the largest parallel surfaces. This is the one item on the list that costs money, and it is also the one that improves every call permanently.
5. Microphone gain is set too high
Over-driven microphone gain is often applied to fix a “we can’t hear you” complaint. It raises the room’s noise floor and the speaker bleed along with the talker, pushing echo back above the cancellation threshold.
The fix: set gain so a person speaking normally at the far end of the table reads healthily, then stop. If that is not enough level, the answer is another microphone, not more gain.
6. The USB run is too long
Passive USB cable beyond about 5 metres causes intermittent audio dropouts and timing errors that break echo cancellation in ways that look random. It tends to appear months after installation, when someone reroutes a cable.
The fix: active USB extension or an extender designed for the distance, not a chain of passive cables.
When it really is the system
If you have ruled out all six and the echo persists, check firmware on the room system and the DSP, and confirm the platform’s own noise-suppression settings have not been overridden. Beyond that you are into signal-flow diagnosis, which is where a site visit earns its cost.
A practical order of attack
- Ask everyone in the room to leave the meeting on their own devices, and test again. This resolves most cases immediately.
- Check whether the microphone and speaker belong to the same device.
- Clap once in the empty room and listen. If it rings, the room is the problem.
- Look at microphone gain before touching anything else.
- Check the age and length of the USB run.
ZenjMedia designs, installs and supports Teams and Zoom rooms across Boston and New England. If a room in your building has never quite worked, book a room review and we will tell you what it needs.
