I thought I should explain to you what a synthesizer headphone is. I know a lot of you probably haven't heard about this sort of thing, but it is very important to the music that you hear.
Basically, when the synthesizer was created, it revolutionized the way that we listen to musical instruments today. When you listen to an acoustic guitar you can hear the great sounds it produces.
The same isn't true for an electric guitar. Without any hook ups, an electric guitar sounds literally like a bango. The synthesizer is the ability to hook up your guitar to speakers or your headset and it produces the sounds that we know as the electric guitar.
Essentially a synthesizer headphone is one that has the ability to hook up to your guitar and produce the sounds that the guitar is making. There are a lot of headphones out there, but you need a special one that can interpret the electrical signals in the guitar to analog sound waves that we can hear.
Typically it is important to listen to these headphones as you play, so you can really hear the sound of your guitar as you're playing. There are a lot of manufacturers of this type of synthesizer and it is available to consumers. You can typically find it at your local music store or guitar store. They'll have the equipment for you, even though it will cost you a little bit of money.
Here is a video of Rush playing a classic song of theirs (Closer to the Heart). You can see that they're all wearing synthesizer headphones, which allows them to hear the real music.