Figure 1.

Schematic representation of the experimental paradigm. During scanning, four different combinations of sound sequences with fixed pitch or randomly changing pitch (Δ pitch) and fixed azimuthal location or randomly changing location (Δlocation) were presented. For each sequence, the first and last elements were identical in both pitch and spatial location (0° in azimuth illustrated here: in the experiment, randomized 0, 90, 180, or -90° in azimuth). Each combination of sound sequences corresponded to a different condition with a distinct percept: 1, fixed pitch, fixed spatial location; 2, changing pitch, fixed spatial location; 3, fixed pitch, changing spatial location; 4, changing pitch, changing spatial location. Additional conditions used during scanning (not shown) were broadband noise sequences with fixed or changing spatial location, and silence. The use of musical notation here is purely symbolic. Pitch variations were random and based on a 10-note octave rather than the Western musical scale. For ease of illustration, short sound sequences with large spatial steps are shown; however, the actual sequences used during scanning comprised 23 or 25 elements with steps of ±20, 30, or 40° between successive locations.