What causes Unity sidechain ducking pumping on sustained music?

The duck volume compressor on your music bus has a release time too short for the sidechain source, so the music gain snaps back up between words and audibly pumps.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix Unity Sidechain Ducking Pumping on Sustained Music

Quick answer: Lengthen the compressor's release (and a touch of attack) so the music recovers smoothly between dialogue syllables instead of bouncing back instantly between every word.

Pumping is a release that is faster than the rhythm of the trigger source. Slowing the release so the music returns over a held note, not between syllables, removes the audible breathing.

How to fix it

1. Lengthen the release

On the Duck Volume effect (or compressor) on the music bus, increase Release to several hundred milliseconds so the music does not jump back up in the gaps between words.

2. Add a little attack

A small attack time softens the initial dip so the duck eases in rather than clamping the instant dialogue starts, reducing the pumping impression.

3. Send only the trigger to the sidechain

Make sure only dialogue feeds the sidechain send, not all SFX, so brief unrelated sounds do not retrigger the ducking and amplify the pumping.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every Unity error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.

Reproduce it once with full context and the fix writes itself. The hunt is the expensive part.