What helps me is to concentrate on feeling where the notes vibrate. I "aim" the "pure head" tones at the top of my head, about 2" above the bridge of my nose.
There's the added complication, of course, that once you've "got" head tone, you then have to add back in all the depth of resonance to make sure you get the full overtone series, and not just a pure white high pitch.
Good luck
K === On Neil Shicoff - http://www.radix.net/~dalila/shicoff/shicoff.html On yours truly - http://www.radix.net/~dalila/index.html
+-------------------------------------------------------+ | For what is your life? It is even a vapour, that | | appeareth for a little time, and then vanisheth away. | | - James 4:14 | +-------------------------------------------------------+
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