I generally use earplugs on any freeway ride over 30 minutes. I have pretty good full face helmets that are reasonably quiet. I use a pair of Sony ExtraBass ear buds with good success. They make a good seal in the ear and are low profile. I use them with and without music. They are comfortable enough to sleep in when camping, when my riding buddies are snoring loudly nearby or if it is real windy. They are inexpensive and durable.
Lately, when not listening to music, I am using the Surefire earplugs (http://www.surefire.com/tactical-equ...rotection.html
) available at gun stores for $10-15. Don't freak when you look at the website and see prices, they list the by-the-case price next to the single price. They are about the best earplugs I have found for the money, almost totally blocking out the sound, they come in sizes, so it is easy to get a good fit. I am using the EP5, in size medium. They fit in ear, are low profile and work so well that I use them when shooting at the pistol range. Also comfortable enough to sleep in when camping with loud snorers or parties near by.
But...the absolute best earphones that I am using are the Bose 20i noise canceling earphones (http://www.bose.com/controller?url=/...ones/index.jsp
) for iPhone, also made for other phones. These can be used to listen to music or make calls. They ain't cheap, but amazing, almost totally eliminating any external noise, allowing you to listen to music at 'normal' volumes. The amount of noise reduction is 'spooky'. When you are at freeway speed and switch them on it is very weird, as everything goes quiet, like the world has almost stopped. The are fairly low profile, fit in your ear, and have different size tips for a good fit, rechargeable 16 hour battery. The take a little effort to get your helmet on without dislodging but I can do it pretty easy. I travel a lot on airplanes and can sit right next to the engines or in front of a screaming baby with no problem. They are pretty cool. Check them out at a Bose store, they have an jet engine simulator in the store and you see for yourself if they will work for you. Plus they have a good return policy if you don't like them. Can't sleep in them for camping, but I always have a pair of the surefire plugs with me for that.
Tried helmet speakers and couldn't make them work for me, no quality and just more loud noise. I have heard that some of the bluetooth headsets have pretty good quality and you also can gain intercom and other communication possibilities.
Good luck with search.