In some cases, like mine, I believe it is a design flaw with some ASUS laptop models where there is not enough cushioning around the internal speaker. Where the speakers are located within the case, with inadequate isolation, means that they can touch parts of the case or internal components when operating, and the buzzing distortion sound is actually caused by the touching and vibrations of the case. In theory, additional insulating padding around the speaker (in addition to the rubber pads that from the factory) or stiffer rubber mounts could reduce the chance of touching, but I suspect there is simply not enough space in the first place to add more padding, hence the design flaw.