Roy,  Could it be you're hearing the first two thirds of a Ruby-crowned Kinglet.  I have heard them do just part of the song.  Another long shot is the alternate song of the Golden-winged Warbler.  Nothing like the "bee-bzz-bzz-bzz" we're use to.  I've heard in NJ, but never in Vermont, and it's not described in any field guides I know, but it might fit your bird.  Sorry I can't describe it in detail.  It's been a long time.  We spent a half hour on a World Series trip trying to identify it before we saw it sing.  Bruce Peterson

On 4/29/10 11:48 AM, "Roy Pilcher" <[log in to unmask]> wrote:

I first heard the song at Aitken State Forest on 2010-04-22 and then again
today on 2010-04-29 also at Aitken State Forest but approximately half a
mile  separation.
From the "heft" of the song, it would suggest a warbler size  bird.
The song was intermittent.
The song seemed "hurried"  almost "explosive".

Bird was up slope when heard on 2010-04-22 in what appeared to be pure
deciduous woods.  Today, 2010-04-29, the song came from a small  stand of tall
spruce/fir, [my tree ID is lacking] and high up.
Song is a trill fallowed by a chu chu chu.  Most times there are three  chu
chu chu's but occasionally two or four.
Caution! I may not be hearing the full song as I have lost and am losing
the higher frequency sounds.
If I get some  leads I can check with the Cornell site, but hopefully there
will be the  opportunity for a some additional ears!
Thanks in  anticipation.

Roy Pilcher
The Gables at East Mountain, Rutland,  Vermont

Speaking the same language.