Diagnosis
Mostly normal. The ONE has a high-speed motor in a compact housing. Certain pitches happen with specific load types, like crushing ice.
How to Fix It
Ensure you are using the correct speed for the task. Start low and gradually increase speed. Use the tamper to keep the vortex going, which reduces cavitation noise. Place the blender on a stable, non-slip surface.
If That Didn't Work
An abnormal noise is a grinding or metallic scraping. This points to a failed blade bearing or debris in the drive socket. Stop use immediately and inspect.
Heads Up
The noise level is inherent to its power. It is not a defect. Do not try to muffle the sound by placing towels under it, as this can block ventilation and cause overheating.