Changes in ANC are usually caused by the following reasons. Please check each one:

1. Smart Conversation is enabled: When you speak, the earbuds automatically lower the volume and switch to Transparency mode to facilitate conversations. After about 5 - 10 seconds, they automatically return to the previous mode.

2. Wind Noise Reduction is enabled: When you enter a windy environment, the wind noise reduction algorithm activates, and it turns off when you leave. This can cause brief changes in the ANC effect during transitions.

3. You are using Adaptive mode: ANC adjusts in real time based on ambient noise levels. In noisy environments, ANC becomes stronger; in quiet environments, it may switch to Transparency mode. This is normal.

4. You removed one earbud: When using both earbuds in ANC mode, removing one earbud will cause the other to switch to Normal mode automatically. When you resume using both earbuds, they will switch back to ANC mode. This behavior is normal.

If you encounter any other issues or your issue has not been resolved, please contact us for further assistance.