Im not a wiccan, so I'll answer you from druidry's perspective. According to the ancient druids' belifs, the entire world is made of vibrations or sound. So yes, music and sound in a broader sense, are not only important, but essencial.
In the case of a spell, in example, the words are important, but also intonation, strength, tone... so a spell casted and not properly pronounced, will not have the desired efects.
That is the reason of why most of knowledge of druids disappeared: it was forbidden (and impossible) to transcribe all these shades down.
the third principle of hermetics dictates that everything vibrate to a degree or another, so yea music does help while practicing magic... but do mind your choice of music sometimes some songs have a good effect on the magus while some will simply take away all your energy though the effects of music does not limit strictly to the mood of the caster they will also may influence the spirits (Well if you practice conjuration like Enochian Magic for example) for example the spirit may be grateful or will simply become angry with you