I do a lot work with power tools, and hearing protection is important to me. However, I also like to listen to music. Although you can buy earmuffs with headphones, I already had several pair of each separately. Here is a step by step process (total time about 20-30 minutes) for combining the two.
Step 1: Parts Needed
All you need for materials are some headphones (earbuds, helmet phones, other), a set of hearing protection earmuffs (the higher the NRR the better), hot melt glue, and electrical tape.
Step 2: Tools Needed
Tools include a drill, drill bits, hot melt glue gun, high speed rotary tool with cutoff wheel, files, measuring device, a knife, a clamp, and a socket.
Step 3: Separate the Earmuffs
Use a knife to carefully separate the ear cushion from the hard plastic shell. Starting at the corner seems to be easier. Different muffs may be assembled slightly differently.
Step 4: Remove Foam
Once the outer cushion is off, remove the foam insulation from inside the hard shell.
Step 5: Measure and Drill for the Cord
For the Chill Pill Helmet Earphones used here, they have a detachable cord. Measure the plug diameter and select a drill bit of approximately the same size (5/16" in this case). On the base of one of the ear pieces, drill a hole for the connector. Depending on the size and shape, you may need to widen the hole by angling the drill bit and/or by using files. Clean up the hole with a knife and verify the fit.
Step 6: Secure Plug
Press the connector plug into the hole from the inside of the earmuff shell. You can use a small clamp and a socket to press it in if it is a tight fit. Once in place, hot melt glue the cord from the inside.
Step 7: Layout for the Speakers
The speakers used in this project have two different cord lengths. The short one will go in the side with the connector plug, and the long one will run over the top of the earmuff head band to the other side.
Step 8: Cut Holes for the Speaker Cords
If the removed ear cushions have a flange, cut a slit for the speaker cable with a cut-off wheel and rotary tool in the center of the top of the cushion. Only cut through the flange. Mark the location of the slot on the hard shell. Measure the diameter of the speaker cables and select a drill bit that is about the same size (slightly larger). Drill a hole for the cable very close to the edge, and then cut a slot to the edge with the rotary tool. Do this to both left and right.
Step 9: Install the First Speaker
The earmuffs used in this example have two layers of foam. Reinsert the first layer and the hot-melt glue one speaker to the foam. Route the extra cable behind the foam and then through the slot that was cut in the top of the hard shell. place the second layer of foam over the speaker, and then press the ear cushion back into the hard shell, being careful to line up the slot with the cable.
Step 10: Install the Second Speaker
Stretch the second speaker cable up and over the headband and repeat the speaker installation for the other ear: insert one peice of foam, hot melt glue the speaker, and put the cable in the slot. Make sure the cable length over the headband is sufficient for the full extension of the headband before putting in the second piece of foam and finally reinstalling the ear cushion.
Step 11: Secure the Cable Over the Headband
Lay the cable over the headband and adjust the headband and earmuffs so the cable is relatively taut. Stretch a piece of electrical tape over the band, securing the cable to the band. Trim the excess tape with scissors, and smooth the tape in place.
Step 12: Connect and Enjoy
Connect the headphones to an MP3 player or phone, and enjoy some music while protecting your ears from machinery noise.