Choir acoustics is but one facet of choir-related research, yet it is one of the most tangible. Several aspects of sound can be measured objectively, and such results can be related to known properties of voices, rooms, ears and musical scores. What follows is essentially an update of the literature overview in my Ph.D. dissertation from 1989 of empirical investigations known to me that deal specifically with the acoustics of choirs, vocal groups, or choir singers. This compilation of sources is no doubt incomplete in certain respects; nevertheless, it will hopefully prove to be useful for researchers and others interested in choir acoustics.QC 20200324Also published in TMH-QPSR 43(1), 1-8, 2002.</p