Hyperbolic location errors due to insufficient numbers of receivers

Animal locations are sometimes estimated by measuring the difference in tra vel times of their sounds at pairs of receivers. Ideally, each difference s pecifies the animal's location to a hyperboloid, and sufficient numbers of intersecting hyperboloids specify the location. Most bioacoustic publicatio ns state that one needs three receivers to locate animals in two spatial di mensions and four receivers in three spatial dimensions. However, the actua l numbers of receivers required for locations in two and three dimensions a re four and five, respectively. Significant location errors can result from using insufficient numbers of receivers. Methods are provided for determin ing locations of ambiguous source-location regions. (C) 2001 Acoustical Soc iety of America.