Part of my ongoing work in magic has involved experimenting with vocal tones and vibrations via my vocal cords. In my daily Tumo practice, I've been altering the position of my tongue on the roof my mouth and have noted that moving it to different parts of the roof of the mouth alters the tone of the vocalization. This work is informed by a recognition of the following principle mentioned in the Spiritual Dimension of Music:
The ancient metaphysicians and magicians repeatedly taught that the actual physical emission of sound, particularly of selected frequencies and patterns was a reflection of an inner spiritual reality. This inner reality has the potency of transformation , both personal and impersonal.
In Tibetan Shamanic and Tantric practices as well as in specific Western mystery practices the physical emission of sound is used to trigger specific states of spiritual power. For example, in my daily practice of Tumo, I vocalize the word Hon and utilize the vibration to invoke a specific union of my energies with the energies represented in that sound. There also techniques where a person can vocalize the different names of God in order to involve the energies of those names into his/her own personal energy.
Breath also plays an important role in this work. Breath is representative of spirit and is also what is used to fuel the vocalization of a sound. There is actually a way to learn how to continue emitting a noise, while drawing in a breath, without much break in the making of the noise.
What I've found in my own work is that there is a definite triggering of a state of mind that occurs with the vocalization of sound. The experience of that state of mind can be quite useful in ritual work as it helps to set up the ritual space/time a person works in. I'm even reminded of an exercise that I and some other people did, from the Possible Human, that involved making a ZZZ sound that signified the passing from one unit of time to another unit of time. At first all of us felt self-conscious, but then we found that the noise actually triggered a shift in time, and that doing the sound with others enhanced the effect.
I suspect the same is true in general. If you make a specific noise with others, for the intent of creating a specific state of mind or metaphysical being, the combination of your sound with others enhances the overall effect. Perhaps this is also because all of the people are experiencing a shift in consciousness to a similar altered state of awareness and the actual altered state of awareness builds of one person supports and enhances that of other people as well. Perhaps its a combination of the above. I do know that the use of sound in magical work is really effective and that turning your voice into a magical tool can be useful for a variety of practices both in meditation and more practical applications of magic.