I’ve never been quite happy with “Sub-Delta”. As far as I’m concerned, Delta ranges from the lowest frequency that can drive entrainment to the frequency where unconscious mingles with consciousness at the Delta/Theta transition. Each person has their own dominant frequencies within each range, so upper and lower limits of a range vary with the individual.

Assuming that the low end of Delta is the lowest frequency that entrains, any lower/sub frequency will not function by entrainment. That means another mechanism to explain AVS effectiveness would have to be  found.

In some cases anecdotal evidence is so overwhelming that some magic may be admitted. We have the matter of whether binaural beats work. The simple answer is, “Yes. They work, but…”

Binaural beats do not cause corresponding EEG rhythms anywhere on the cortex – they do not cause entrainment. There is another mechanism whereby binaural beats assist the subject by supporting thought modes typically associated with the target frequency. The most interesting things with binaural beats take place at very slow beats (0.5-1.0Hz) on very low pitches (20-40Hz depending on bass capability of listening system, and always maintaining an exact multiple of the beat).

Why arbitrarily assign a frequency somewhere in low Delta below which is Sub-Delta?  Finding the lowest frequency you can entrain to is good use  of  an EEG device – using monaural or isochronic beats, of course. This frequency is the low end of Delta for you and there’s no apparent reason why anything below should be of use – unless the objective is to induce coma – no magical explanation necessary. “Low-Delta” is a much more satisfactory concept.


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  • Skebnar  On May 21, 2011 at 6:48 pm

    Great to see you back, Craig!

    Binaural beats do entrain the brain, just different structures than light does, and the frequency range is more limited (lower freqs, not much good above ca. SMR range). Never experimented with delta and sub-delta, due to studies indicating not much frequency following effect happening there.



    • CraigT  On May 24, 2011 at 4:32 am

      Thank you.

      I have a particular definition of “entrainment” which requires a measurable response over the sensory region and over a relevant functional region. Binaurals often lead to a relevant rhythm being found over a functional region, but they do not show up over the auditory cortex. Other types of beat, such as monaural or isochronic do show response over both sensory and functional regions.


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