When improvising pure vowel tones and overtones, the voice is used as a non-verbal musical instrument. When chanting, the voice is the carrier of The Word, which is, itself, a facet of vibration. R J Stewart has this to say about chanting with the voice:
The most important asset of the human voice is that it acts directly upon the physical organism in some very distinct ways, which have been the subject of study and practice for many thousands of years in magical and spiritual disciplines around the world. The results of this art of empowered voice may heard not in classical music or opera but in liturgical chant or plainsong, shamanistic chants, epic magical narrative singing, temple chants throughout the East and in the truly immense protean collection of ritual chanting that permeates all cultures worldwide. Remnants of such ritual chanting are even found in Britain, in outlying areas. (From Music and the Elemental Psyche)
During a sound journey, you may hear both improvised pure vowel tones and chants from around the world, including the British Isles.