Changes in Timbre of Sounds with Changes in Elevation

The graphs are transfer functions, which compare the intensity of various frequencies of sound received by the ear to the intensity of these frequencies received by a microphone in open air. For ease of comparison, the 0° transfer function (green) is superimposed on the transfer functions obtained at 60° (red), 30° (orange), and –30° (blue). The differences in the transfer functions at various elevations provide cues that aid in perception of the location of a sound source. (Adapted from Oertel, D., and Young, E. D. Trends in Neuroscience, 2004, 27, 104–110.)