I'm having trouble finding information about an electronics company's patent information for each of its headphones.
You will find the federal government's patent database at http://patft.uspto.gov/. You can do a Quick Search of patents and put in your company names to see what patents the company has.
It's possible, though, that the company wouldn't have headphone patents, necessarily. If you want their product specifications, you should check the company product Web site.
For information about patents in general, you may want to check the Patents research guide from MIT libraries at http://libguides.mit.edu/content.php?pid=239146&sid=1973230.