If you take the covers off your cd players or your computers, you'll find that inside, the circuit boards are made of epoxy resins . Here's another place where it pays to be a good insulator. Next we can take a look at these speakers. The cones of woofers and tweeters are often made of paper. I'm sure you've seen it before.
Paper is a form of cellulose , which is one of many naturally occuring polymers .
Of course, if you look at the high quality speakers like this subwoofer, then you'll find cones made of a plastic called polypropylene . An alternating field makes it vibrate, and the vibration can be made to produce sound. Here's an assembled speaker for those who don't feel like building their own. It's cabinet is made of wood. Wood is another form of cellulose .