Distributed around the outside of the dryer's drum would be several pivoting mechanisms that swing outward due to centrifugal force (yes, physics buffs, I know, but "centrifugal" is fairly intuitive) as the drum rotates. At the dryer's normal rotational speed, the pivoting mechanisms would be nearly perpendicular to the tangent of the drum (straight out).

Attached to each of the mechanisms would be a metal bar, mounted and sized such that each would resonate at a different frequency when struck hence creating a rotary xylophone. (Ok, not technically a xylophone I suppose. "Random Rotary Glockenspiel" perhaps?) As the dryer rotates, the bars are swung out in to the path of a spring mounted mallet/hammer which would strike the bar as it passes.

The irregular thumping of the dryer load comes in to play...to get a more or less random, wind chime type effect, the individual notes would be latched in close to the drum, out of reach of the hammer. A release mechanism on each note would extend to the inside of the dryer drum and would be released when sufficient force of falling clothes strikes the release mechanism.

After being hit by the mallet, the note would be reset back to its latched position as it passes a sort of ramp device which would push it back inward.

Annoying, but useless.