This is going to be a very short and simple tutorial for making an audio modifier. I should mention right off the bat that this isn't anything crazy, and it's not the kind of modifier that's going to make your voice sound like a dalek, but it's pretty interesting and I highly recommend trying this project out. Also, this is my first Instructable and I'm only 14 years old, so I would love any feedback from you people. Without further ado, let us begin.
Step 1: Buy an Auvio Headphone In-Line Volume Control
This is the only thing you're going to need for this project, other than some basic tools. As the title says, this is an Auvio Headphone In-Line Volume Control, It has a simple 3.5mm audio jack, 4 feet of cord, and then a little piece where you can adjust the audio and plug in your headphones. I found this at RadioShack for $10, but I'm sure it's sold elsewhere and possibly for cheaper. Anyways you're going to need to buy this and pull it out of the packaging.
Step 2: Open the Volume Controller
This step is also pretty simple. All you need to do is get a small screwdriver or something similar, and gently pry open the casing of the volume controller. It should pop off and you'll be left with half of the casing and a pretty simple circuit board. On to the next step!
Step 3: Disconnect the Ground Wire
On the right of the circuit board there should be three wires coming up and connecting to the board. You're going to need to find the golden ground wire, circled in green, and either desolder it from the board, my personal choice, or simply cut it. Either way, you're probably going to want to cut the ground wire short afterwards to keep it from interfering with anything else. The reason we're doing this is because this means that after the audio goes through the headphones, it attempts to ground itself, but since there's nowhere for it to go, it hangs around and messes with the audio. Not only does this create a slight echo, it also ends up muting some sounds in whatever music is being played, often leaving only the harmonies playing in a song. I'm not completely sure how it works, but I'm glad it does because it makes some songs sound pretty interesting. Experiment with it and find what songs sound the coolest (if you want a quick example, listen to Galaxies or Fireflies by Owl City).
Step 4: Put Everything Back Together
Snap the casing back on, and BOOM, your very own audio modifier. I know it's nothing to extravagant, but it works, looks nice, and isn't too expensive. As I said, this is my first Instructable so please leave some feedback in the comments, and if you'd like I can post a video of what some songs sound like so you have an idea of what you're making. Anyways have a nice day and happy building!