What The Psychedelic Society have to say about their event:

“Psychedelic experience without psychedelics”.

As you lie on a mat on the floor, gongs, singing bowls, other ritual instruments and voice will be used to weave a tapestry of sound. 

The vibrations create a feeling of being 'bathed' or carried away into the space, with participants variously reporting subtle or powerful bodily sensations, a deep meditative state often accompanied by rich imagery and visions, or feeling of timeless nothingness and bliss. During the session the brainwaves are altered to the state that is self-healing, and has balancing benefits on the body and mind. Occasionally some sounds might trigger unpleasant and suppressed emotions that flow up to the surface — please accept them as a part of a healing process. In most cases the overall experience is very relaxing and ecstatic, and participants feel refreshed and recharged for a few days after the session.