iPod headphones have many features which work best with the iPod interface, but some materials are used just because they are the best of what is around. This is why Apple used neodymium magnets in the construction of their headphones. Neodymium is much more magnetic than a ferrite magnet of the same size and does a much better job of capturing the acoustics of a performance without loss.
This means that you can get premium dynamic sound from your iPod ear buds that would formerly have only been achievable through circum-aural headphones. Since their inception, many other companies (such as Bose and iFrogz) have used similar methods and materials to create similar sound in ear bud and ear canal format. www.aimmagnet.com