Although not actually required music is a great tool for relaxing and can help enhance the hypnosis experience. Although everyone is different and may vary a great deal in what your likes and dislikes are you are in my opinion better to listen to either New Age, Classical, Natural Sounds or similar, rather than Heavy Rock, POP or RAP.
However saying that, if you really can't stand all the usual relaxation style music and you do in fact genuinely use the likes of Eminem, Queen or Lead Zeppelin etc to relax then so be it... ! the whole purpose of using music is to let your Mind wonder and loose yourself in it, however you do not want to get involved in it and end up singing along!!
How To Use Audio Entrainment CD's.
These are examples of typical music people use to chill out to. But there are thousands to choose from!