[Taxbilly]

Then did you meant to say it was the sound of "Woo" not sounded like "woo?"
It seems unlikely that they would be shouting "Woo" at Bush at this time in his oratory.
woo   
v. wooed, woo·ing, woos
v. tr.
To seek the affection of with intent to romance.

To seek to achieve; try to gain.

To tempt or invite.

To entreat, solicit, or importune.

v. intr.
To court a woman.

Could it have been the word "who" you heard the crowd yell? For the pitch of "who" does not attain the higher pitch of "boo" that we agree was not uttered during the collective response of this well mannered crowd?

[Robert A Cook PE]

"Oooh."

A sound of shock, caused by sudden intake of breathe by hundreds in surprise and shock at bad news!

[Lexinom]

Could it have been the word "who" you heard the crowd yell?

That depends, billy. What would, in your estimation, be the quantitative likelihood that a sizeable enough contingent subset of the crowd suffered from aural impediment? We need a study, darn it! :-)

[gogipper]

I was there. There may have been some 'whew' s because of the surprise of the malady. He does seem like a young man.