From the Editors of The Daily Cat
From a physical standpoint, loud noises emitted from televisions, stereos and other equipment won't hurt your cat's hearing, especially if your pet can move to a quieter room.
Keep in mind, however, that your cat's hearing is at least six times more sensitive than yours. If music or TV sounds blaring from a speaker seem loud to you, imagine how your cat feels about them. At the very least, you could be giving your kitty a major headache.
Try to keep your television at a reasonable sound level. If you like to listen to loud music from time to time, consider buying headphones. Many high-tech gadgets like iPods allow you to set a maximum volume, preventing your own hearing problems from developing. In terms of your cat, such volume limits come in handy if you plug your MP3 device into external speakers.