While scientists and philosophers have been interested in sound source localization since the time of the ancient Greeks, the modern study of this topic probably began in the late 19th century. Because sound has no spatial dimensions, there were many arguments at this time as to how humans localize a source based on the sound it produces. Lord Rayleigh conducted a “garden experiment” and concluded that a binaural ratio of sound level at each ear could account for his ability to identify the location of people who spoke in the garden. This type of experiment began the modern investigation of the acoustic cues used for sound source localization. In the first half of the 20th century, psychoacousticians such as Licklider, Jeffress, Mills, Newman, Rosenzweig, Stevens, von Hornbostel, Wallach, Wertheimer, and many others (documented by Boring in Sensation and Perception, 1942 and by Blauert in Spatial Hearing, 1997) added seminal papers leading to our current understanding of sound source localization. This pr...