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During the opening and closing process of a foldable screen phone, multiple flexible materials and components come into contact and move against each other. Slight friction and air gap noises are difficult to avoid completely, but the sound levels are within standard ranges.
The hinge of a foldable screen phone is a complex mechanism made up of multiple interlocking parts and precision components. During the opening and closing of the screen, the rotational friction between these parts will produce slight noises. This is a normal phenomenon.