The purpose of this study was to compare cortical brain responses evoked by amplitude modulated acoustic beats of 3 and 6 Hz in tones of 2 Hz with those evoked by their binaural beats counterparts in unmodulated tones to indicate whether the cortical processes involved differ. Pratt, Hillel Starr, Arnold Michalewski, Henry J Dimitrijevic, Andrew Bleich, Naomi Mittelman, Nomi PMID:22326292Ī comparison of auditory evoked potentials to acoustic beats and to binaural beats. The Weber fraction for detection of an increase in binaural beat rate is roughly constant across beat rates, at least for rates above 4 Hz, as is rate discrimination for SAM tones. The matched-salience SAM tones had relatively shallow depths of modulation, suggesting that the perceptual strength of binaural beats is relatively weak, although all listeners perceived them. The results indicated that discrimination acuity for binaural beats is similar to that for SAM tones whose depths of modulation have been adjusted to provide equivalent modulation salience. Twelve normal-hearing adults participated in this study. Rate discrimination was measured for standard rates of 4, 8, 16, and 32 Hz – all in the 500-Hz carrier region. The purpose of this study was to gauge the strength of the binaural beat percept by matching its salience to that of sinusoidal amplitude modulation (SAM), and to then compare rate discrimination for the two types of fluctuation. Previous studies of binaural beats have noted individual variability and response lability, but little attention has been paid to the salience of the binaural beat percept. Some neurons in our sample responded selectively to manipulations of these two variables, which suggests a sensitivity to direction or speed of movement. In addition, this stimulus allowed the direction and rate of interaural phase change to be varied. The response of most cells was phase-locked to the beat frequency, which provides a possible neural correlate to the human sensation of binaural beats. The interaural phase sensitivity of neurons was studied through the use of binaural beat stimuli. Response of cat inferior colliculus neurons to binaural beat stimuli: possible mechanisms for sound localization.
0 Comments
Leave a Reply. |