Lucier's Vespers (1968) focuses on auditory perception and spatial orientation. Despite the possibly ironic reference to religious music, the name Vespers refers to vesper bats, or evening bats. These animals navigate space through echolocation — the ability to recognise space by listening to the reflections of emitted sounds. Their spatial awareness is auditory rather than visual.
In Vespers, performers are equipped with hand-held echolocation devices (clickers) emitting short, sharp sounds at variable intervals. While listening to these pulses and their reflections from the walls, the blindfolded performers can explore the spatial characteristics of the room using only sound.