Rotating tones and binaural beats

Abstract

This study investigated rotating tones and binaural beats as a function of the frequency of the standard signal (f0) and the interaural frequency ratio (f1/f0). Both beats and rotating tones ’’disappear’’ as the frequency of the standard signal is increased. Using a 2AFC procedure, the upper limits for rotating tones and binaural beats were estimated to be 1170 and 1255 Hz, respectively. Rotating tones were observed with large interaural-frequency ratios and were observed almost exclusively with the perception of a single fused image. Binaural beats were obtained with smaller interaural-frequency ratios and nonfused images (a separate tone was heard at each ear). The present results suggest that binaural beats and binaural rotating tones may be mutually exclusive phenomenon, with the latter being dependent upon both the binaural capacity to fuse disparate signals and the peripheral auditory system’s capacity to code the temporal information in the signal’s microstructure.