LOUP Engineering: AEC & DSP · advanced
Removing the Downlink Suppressor Improved the Stable Build
More signal processing is not automatically better audio.
Removing the Downlink Suppressor Improved the Stable Build became a separate note because the failure crossed more than one subsystem. The V132A direction kept AEC but removed the downlink suppressor after testing showed clearer, less robotic audio without that stage.
Suppressors can reduce noise or echo-like energy while also damaging speech transients and naturalness. Once the AEC reference and playout path were behaving, the extra downlink processing no longer justified its artifacts. The correct comparison was processed versus unprocessed under the same call conditions.
The fix came from assigning one owner to the behaviour and refusing to hide a hardware or network fault with an unrelated firmware workaround. Evidence marker: remove-downlink-suppressor.
Every DSP block has a cost. Keep a block because measurements and listening show it solves a real problem, not because the diagram looks more complete. The value is not only the fix itself; it is having a repeatable way to prove the same class of failure has not returned.
Project evidence
LOUP engineering marker: remove-downlink-suppressor. This note records the design or debugging lesson without publishing device credentials, private keys, customer data or manufacturing secrets.