Since a number of contesters have discovered the benefits of Bose noise-cancelling headphones, this may be of interest.

I've seen various attempts to add a Heil boom mike to Bose phones, usually involving "Velcro(R)-brand hook-and-pile fasteners" or duct tape, or rubber bands. These arrangements have generally been unsatisfactory for a variety of reasons. I wanted something more solid and sturdy. This version is pretty solid, only takes 30 minutes or so and inflicts minimal cosmetic damage to the Bose phones. And the mike can be removed for CW contests.

I got a pair of the new, improved Bose phones for Christmas (Model QC-2 - they fold flat for traveling, etc.- they are very nice). I figured this gave me the freedom to experiment with the old ones. Incidentally, I do not recommend messing with the new model since there are wires running through the headband to connect the right and left earphones, and drilling through the plastic will likely destroy that wire. The headphones you want to modify are the original Quiet Comfort - they are no longer in production, but show up on eBay for $150-175. The noise cancelling circuitry lives in a small plastic box that connects by a wire to each of the headphones. Some contesters have experienced RFI on some bands when RF gets into the little box - I found that wrapping the cord that connects the little box to the rig around a Radio Shack split ferrite bead 5 or 6 times fixed it.

UPDATE: My QC-1 developed a problem after >5 years of use, so I decided to examine the QC-2 a little more closely for possible modifcation. I discovered that the wire in the headband can be avoided if you are careful, and I now have added this mod to my QC-2 phones, which fold flat for traveling. They do not have the little box, since all the electronics for the noise cancellation are included inside a little gadget that slides inside the left earphone cup, and the battery slides into the right earphone cup. I used them in the WRTC2006 competition in Brazil.

The parts needed for the mod are available as replacement parts for the BM-10 and BM-5 headsets sold by Heil sound (www.heilsound.com). These are the headphones that sit on your ear with little foam pads. I never liked those headphones. If you already own a pair of them, you have the parts already. You need the following:

BC (Boom Clip) - buy 2 or 3 of these...they break easily

BM Boom

BM Mic cup

BM Screen

BM Cord (not necessary if you already have some really small diameter shielded wire that fits inside the boom tubing) 

And of course, a mike element - probably the HC-4 for hard core contesting.

You will also need two small (2-56) machine screws - 3/4 inch long is about right, and these are not available at Lowes or Home Depot - you will need to find a smaller local hardware store. My original version used some small (maybe 2 mm?) metric size screws, but I've been using the 2-56 size lately. You also need nuts to fit, and if you are a perfectionist, lockwashers. I also needed a small washer (you'll see it in the photos) but other people have drilled both holes in the Heil plastic clip and eliminated the washer).

Remove the earphones. All the work is done on the headband - actually on the U-shaped plastic brackets that hold the earphones to the headband (at left in the photo below).

Drill two small (2 mm or 3/32") holes through the bracket, one on either side of the letter "L", extending the existing holes where there are already two screws holding the band together (there are no wires there, so it's pretty safe). This is where you need the two 2-56 screws to go through corresponding holes drilled through the plastic Heil clip.

The little plastic piece in the middle of the picture above holds the bracket to the headband. The small screws formerly went into the main part of the bracket, and will be replaced with the longer screws going all the way through. The photo below shows the first screw installed.

The photo below shows where I sort of goofed and had to use the washer. If I had planned ahead, I would have drilled two holes in the green plastic Heil boom clip so that 1) they would line up with the holes in the Bose bracket, and 2)  the whole thing would be shifted to the bottom part of the bracket to allow more rotation of the bracket. As I did it, I needed that washer, and the left earphone doesn't turn. More recently, I have been trimming off the top half of the round part of the Heil clip (left side in the photo below) to allow the earphone to turn.

So either add the washer or drill the hole in the right place, insert and tighten the screw, and the boom clip is firmly attached to the earphone bracket.

Then the boom mike snaps into the Heil clip, and presto! - you have a noise-cancelling headset with boom mike. You can bend the boom some if you are slow and gentle with it, to get the mike right in front of your mouth.

NOTE: You are on your own if you do this mod. Don't call me if you break your headphones or the mike boom. You assume all risk. Your mileage may vary.