In personal practice I treat background music as a set and setting feature. Within ritual I am trying to craft a "vibe" in the environment as the vibe is going to dictate how present the god/godform is. This provides a lot of flexibility in theory for what type of music you're using for your ritual. I like to put on arabic/egyptian sounding ambient music but I have been known to play some mellow techno if the vibe calls for it.
The relationship between music and the occult is incredibly important and profound, and while in spirit conjuration, personal work, and channeling it is often wiser and suggested that you perform your work in silence (the spirits prefer this) on the other hand of the spectrum when we perform regular ritual for gods, celebration, devotion, and meditation the right music lends to our power of utilizing sympathies to give the diety presence in our environment. Within the classical Mediterranean the utilization of correct incense and smells became extremely important because of a philosophical principle, that is, when we can make the essence of the god sensible we grant it the a sensible root in the material world. As we have five senses this principle can be extended to all of them, when we select the correct music that participates in the essence of the diety then we have given ourselves another avenue to sensibly apprehend the diety we seek contact with. The decorations you choose for the altar, the icons and colors are giving us a visual apprehension of the diety and it goes on and on.
We can dig a little deeper however and look at what music is really about, and within the quadrivium music is Number in Time. So what we ultimately can deduce about its power is that music is an artform about time and our affinity towards it is motivated by our propensity to experience time and appreciate it. This points a little bit towards the power of repetitive and percussive music as we can all draw images in our heads of a tribal shaman dancing to a drum circle, the famed initiatory festivals of the Ancient Greeks in which repetitive music would be used to induce ecstatic states of divine experience, and in modern context we can think of the extreme feelings of euphoria, interconnectedness, and oneness that many ravers/festival goers report feeling (with the help from psychoactives) listening to extremely repetitive electronic music. Something happens within repetitive music, repetitive and percussive music creates feelings of time dilation and the power of music to create this feeling is pointing again to what the occult power of music is. Music gives us the ability to sense perceive time, wield time, utilize time, and transcend it.
So following the quadrivium again we can look at the next subject after music which would be astronomy/astrology. This is Number in Space and Time and this is kind of a syncretic mastery of space and time working at once. As the placement of the planets and stars, and their movement across the heavens, has always been a timepiece that humanity has looked to in order to measure its moment and place in the cosmos. This conclusion became an obsession of the Rennaissance esotericists/occultists and where we get the idea of the "music of the spheres" from. The idea that if music is a sensible experience of time which we are all bound to, then the stars are a reflection of that same principle and something that like music, when mastered, can be used to perceive, wield, and transcend not just time but spacetime. If we can frame astrology the same way we understand music theory then the hermetic secrets of the stars tend to unlock. For example, If we think about an astrological conjunction as playing an octave on a piano then we understand the type of harmony between the two planets. When we see a trine between two planets we can think of that as playing a third on the piano, a square aspect is a fourth which sound often discordant but in context can be used to create haunting tension and the sextile provides us with a perfect fifth.
Looking at music through this esoteric perspective we can begin to utilize it to create harmonic associations within our ritual magic, we can utilize the occult powers of music to engage in that pesky layer of our reality, time, and select music that participates within the essence of diety to give diety the ability to manifest.
Music is about ratios of time and timing, and it provides the unsensible archetypal/noetic forces a medium to become sensible. What music you select, what instruments or genre you use ultimately do not matter as long as they are participating in the occult function. A divine artform about transcending time is not bound by a location in spacetime. You do not need to use ancient Greek hymns or old desert instruments from 2000 years ago, music is timeless.
