Complex sentence: In general, soft'pliable' porous materials, like cloths, serve as good acoustic insulators-absorbing most sound; whereas dense'hard' impenetrable materials, like metals, reflect most.
Split into simpler sentences: In general, soft'pliable' porous materials, like cloths, serve as good acoustic insulators, absorbing most sound. Whereas dense'hard' impenetrable materials, like metals, reflect most.