Ganzfeld produces alpha waves. Is there a biofeedback technique for producing theta?

[tapani]

Zen meditation might work for you.

"The theta rhythm state is defined as a dominance for 4-7 Hertz brainwaves. Transient elevation of theta occur during Zen meditation (Kassamatsu & Hirai, 1969) or while entering the early stages of sleep and are reported to be associated with vivid visualization, imagery and dream-like states. The origin of theta waves is predominately the hippocampus (Michel et al., 1991), although theta activity can be recorded throughout the cortex and cerebellum (Green, Green & Walters, 1971)."

[adelphos16]

Yes, a few companies sell CDs that have a harmonic pattern and claim that listening to it will put you into Theta. The site link included in my reference has quite a few research papers on it. I have a tape from another company somewhere. Its interesting and seems to work although I've never used it while attached to an EEG.