II. Comparison of mono, stereo and 3-Dimensional Living Sound using topographic EEG brain mapping

Studied: Comparison of mono, stereo and 3-Dimensional Living Sound using topographic EEG brain mapping
Conducted by: Gary Schwartz, Ph.D., Professor of Psychology, Neurology and Psychiatry, University of Arizona

In this study, 15 subjects listened to recordings of ocean and various sound effects recorded in mono, stereo and 3D Living Sound. While listening, electroencephalographic recordings of brain wave activity were conducted and subjects rated each audio recording for interest and realism.

The following includes excerpts from the analysis that was performed.

“Subjects rated each tape (during the EEG session) for interest and realism. The line graph shows the results, averaged over ocean and sound effects. A 3 way repeated measures analysis of variance was performed: (1) ocean / sound effects, (2) mono / stereo /3D, and (3) interest / realism. The main effect for mono / stereo / 3D was highly significant (p<.0006). Subjects rated mono as lowest, stereo as moderate, and 3d as highest. There was a significant main effect for ocean / sound effects (p<.039) indicating that the sound effects tapes were rated overall as stronger (7.74). I repeated the analysis of variance for just stereo / 3D (removing mono). The main effect for stereo / 3D was significant (<.037), as was the main effect for ocean / sound effects (p<.012). In a word, the tapes “worked” with these subjects. On the whole, the subjects perceived the mono, stereo and 3D tapes differently. As expected, 3D tapes were rated as most interesting and realistic.

The EEG data were spectral analyzed, saved as ASCII files, imported to Quattro Pro 4.0, transposed and imported to CSS 3.0, and statistically analyzed. Separate analyses of variance were performed on theta, alpha, beta 1 and beta 2, using a 4 way repeated measure design: (1) ocean / sound effects, (2) stereo / 3D, (3) right side/ left side, and (4) site (8 sites each side).

There were no significant effects for theta or beta 2. However, there were significant effects for alpha and beta 1.

First, for alpha, there was a borderline significant ocean / sound effects by right / left interaction (p<.059). Alpha was generally greater for the ocean tapes compared to the sound effects tapes (across both stereo and 3D tapes), and the ocean alpha enhancement was stronger on the left side.”

“Second, for alpha, there was a significant stereo / 3d by right / left interaction (p<.039) and a significant stereo / 3D by right / left by site interaction (p<.018). Alpha decreased in 3D compared to stereo, especially on the left, posterior side of the brain. I have plotted the alpha data subtracting the alpha for the mono data. Again, yellows, reds and whites man alpha increased, blues and blacks mean alpha decreased. You can see that for stereo, alpha increased in the left and right temporal regions compared to mono, whereas for 3D, alpha increased in the right temporal regions but decreased in the left temporal and posterior regions compared to mono. These data suggest that the 3D tapes were more attention getting, novel and interesting compared to the stereo tapes. Note that these effects are independent of ocean and sound effects.

Third, for beta 1, there was a trend for a stereo / 3d by right / left interaction (p<.068) and a significant stereo / 3D by site interaction (p<.022). Beta 1 increased in 3D compared to stereo, especially on the left, posterior side of the brain. I have again plotted the data subtracting the beta 1 for the mono data. Here yellows, reds and whites mean beta 1 increased in the left, posterior regions. These data further support the hypothesis that the 3D tapes were more attention getting, novel and interesting compared to the stereo tapes. The fact that they show up on the left side and the posterior, (rear) regions (occipital) are consistent with the idea that both verbal imagery and visual imagery were activated by the 3D tapes.”

Although these results would, perhaps, be more interesting if you were able to view the referenced graph and topographic EEG maps (which will be provided upon request), the most striking feature of the graph is the fact that subjects rated the interest / realism of 3D so much higher than stereo. In fact, the difference between stereo and 3D was greater than the difference between mono and stereo.

The fact that 3D sound is much more engaging, relaxing and vivid than normal stereo may have particular significance because a correlation has been demonstrated between vividness of imagery and efficacy of therapeutic imagery techniques. It has been hypothesized that because it is more ”vivid” the 3D Living Sound enhances the psycho-physiological effects of the other techniques without being sleep inducing in and of itself.
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