Is it possible to create a voice command attachment for an iPhone 5?

For a senior project at school, I would like to create an attachment for an iPhone 5 that would control the music, without having to press a button like Siri. For example, while listening to music, I would say "pause" and the music would pause, or "mute" and it would mute. Very much like in the iron man movies when tony stark says mute to the tv, it mutes. This attachment would be plugged into the headphone jack. If anyone knows where this has been already created it would be awesome if you could tell me, or if you know how I could do this.

If you jailbreak your phone you can modify Siri to do this.

This is possible with packages installed on a jailbroken device (and packages for this already exist), but an app to do this violates apples policy and is not allowed.

A hardware attachment is possible (iPod docking stations do this) but you would have to plug into the lightning connector and not the headphone jack, as that is sound output only.

You would need to have a mic and firmware to control the commands and send the signal to the device. It's probably too big a project for a high school student, especially with no experience.