Why Does My Product-Demo Voice Echo When I Add a Microphone Source to an OBS Scene?

Distinguish one device from two capture paths

A single physical microphone can feed more than one configured capture path. Seeing the microphone listed once in your equipment inventory does not establish that the scene records it only once.

OBS distinguishes devices enabled globally from Audio Input/Output Capture sources active in particular scenes. Its audio-source documentation warns about echo when the same device is selected through both routes. This is a documented possible cause, not a diagnosis of every delayed or reverberant voice.

Build a routing inventory before changing filters

Write down the exact device selected globally and the device selected in each relevant scene source. Include the opening, demonstration and closing scenes if the capture should change as the presentation progresses. Similar source names are not a reliable substitute for the device selection.

OBS advises disabling the global capture when you intend to add that device directly to scenes. Apply that guidance only to the duplicate device and the intended workflow. Do not mute all global sound indiscriminately or assume that every scene should use identical routing.

A scene-local route can be intentional when a microphone should appear only in selected scenes. A global route can serve another assignment. Choose the intended capture contract first, then review whether the implementation matches it.

Illustrative exercise: two different investigations

Illustrative exercise — fictional configurations, not OBS recordings or listening tests. Case A has the same microphone selected globally and as a scene input. Case B has only one verified microphone route but still sounds reverberant.

For A, preserve the current configuration record, remove the unintended duplicate route in a test setup, and make a short local recording. Listen before and after under the same conditions; do not announce a repair from the source list alone.

For B, do not assert that a second route exists. Record the remaining symptom and investigate the recording or monitoring path separately. A documented cause is useful only when the actual configuration supports it.

Check every scene that needs the voice

After a routing correction, verify both the demonstration scene and the transitions into and out of it. Removing a global route can expose a scene that never had the intended local capture. The useful result is a complete narration path, not simply an empty mixer channel.

Record whether the actual output contains one intelligible voice and whether all required scenes retain sound. Keep unrelated music and device settings unchanged during this comparison so that the observation has a clear cause.

This is source-based troubleshooting for external recording. It does not execute OBS changes, guarantee acoustic improvement or turn a silent generated advertisement into an audio-ready campaign.

Illustrative exercise — device and capture-path audit

These are illustrative exercise rows. Save a copy and record your own observations; the example is not an executed acceptance test.

Download review worksheet (CSV)