Most "clicking" clocks that use batteries have a pulsed electro magnet that moves the parts and in return the fingers.

If that magnet works every second to move a flimsy rocking mechanism you end with noise.

Smarter designs use a mechanism with a pulsed motor, similar in function to a stepper motor, those designs are usually silent apart from a slight noise when the finger is moved (barely noticable even in silent conditions).

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