Janet Cardiff's The Forty Part Motet, a rendering of Thomas Tallis' Renaissance masterpiece Spem in alium ("Hope in any other") c. 1570 is nothing short of phenomenal. This polyphonic choral work is of an early music form known as a "motet", in which varied voices play against one another to create a rich tapestric whole. In this case we have a forty part composition, made up of eight separate five-voice choirs. A beautiful work to behold in its own right, it is further enhanced in Cardiff's separation and spatialization of the voices.

Upon entering the open gallery space overlooking San Francisco's waterfront, one is immediately drawn in by the celestial voices. Forty amplified speakers set at ear-level height are arranged in an oval that fills the area. Along the curvature, the speakers are clustered into groups of five, one for each of the eight choirs. Each speaker gives voice to a single choir member. Moving into the center of the circle, the visitor experiences music in a profoundly unique manner, being completely surrounded and fully immersed in the work. The rise and fall of the varied voices pushing against each other come from any and all directions, allowing the listener to better understand the interplay and dynamism of the motet. Directionality emerges as a key compositional element.

I recall having the pleasure of sitting in close proximity to a live performance of György Ligeti's ethereal choral work, Lux Aeterna (famously used in Stanley Kubrick's film 2001: A Space Odyssey). Each of the singers there was arranged left to right, grouped according to vocal range from bass to soprano. The spatial separation of vocal parts provided an undeniable immediacy to the score, allowing each to emanate from its own distinct location along the lateral axis of the stage. Now, Cardiff's Motet takes that exquisite technique to an entirely different level of immersion within a full three-dimensional environment, creating an enhanced sense of presence for the audience.

Further, as the audience is free to move about the gallery space, one is able to approach each individual speaker or set of speakers, which allows an up close and personal connection to that thread of the vocal tapestry. One is able to focus on the unique characteristics and contributions of that particular singer or group of singers, while never losing the full context of the greater piece. Surely a beautiful piece to be heard as a standard recording, this 3D rendering of the motet promotes active exploration of the composition by all visitors to this sonically sacred space.

These forty disembodied voices, angelic and yet deeply human, provoked visceral reactions from all who shared this intimate space with them. Lovers held each other close. Parents beamed into their child's eyes with knowing smiles. Some stood rapt with their eyes closed, absorbing the complexity of the whole. Others wandered about the perimeter, delighting in the individual voices. Everyone was interacting with the work in their own way. Discovering. Exploring. Experiencing.

Co-presented with SFMOMA, The Forty Part Motet is on display a Fort Mason Center for Arts + Culture in San Francisco through January 18, 2016.