Poor mans noise reduction ear-buds. Many advantages over ($200-$300)Bose: cheaper (pennies on the dollar) and smaller, allows mobility, no batteries required. Using existing (JVC) noise canceling Ear-buds, use Flents (or other manufacturers) spongy-type earplugs in place of the JVC plug. If you have heat-shrink, you can replace and elongate the JVC tube to allow inserting the Flent's plug better into your ear.
Great for planes, bus/car, mowing the grass, loud work environment, etc. Your mp3 player will only require 1/2 volume with these - thereby extending battery life.
Also - See my short 'Video Instructable' for the very same thing.

Step 1: Buy a Pair of (supposed 'noise Canceling') Earbuds

Get some earbuds similar to those shown.

Step 2: Take Them Apart

Pull the blue cushion off the earbuds - this'll be replaced using regular foamy-type earplugs.

Step 3: Trim to Desired Length

If you have some heat-shrink, you can make the tube long thereby using more of the foamy-type earplug. If no heat-shrink, cut to length just exceeding the earbud tube. If the plug is too long, it will squeeze shut where the sound must travel through.

Step 4: Use Heat-Shrink

If you have some heat-shrink, cut to desired length and shrink around existing earbud tube. A longer tube allows more use of the earplug thereby eliminating more external noise.

Step 5: Hole Punch

You must punch a hole thru the earplug, in order to pull it over-top the heat-shrink (or earbud tube). Get a cheap hole punch kit from any hobby store. Squish the earplug into a pancake, place the hole punch on center, strike once with light hammer. Allow earplugs to expand.

Step 6: Assembly

Once the foam has expanded and the hole is thru the middle. Pull the plug over-top the heat-shrink tube. It should fit snuggly so as to not slip off. Some trial and error may be required using different size holes.