Thanks for the replies
I think I'll disconnect the air control motor and drop the bottom of it to see if something's maybe fallen down into the motor or the fan. I really don't think that that's the problem, but, as they say, start with the easy stuff first.
The noise it makes is not like a nail rattling around in a hamster's exercise wheel; it's more like . . . . well , I don't know what it's like. If there's a flapper or door inside the housing there, it may have come loose and it may be letting air through, whoosh-sh-sh-sh-sh, and then flopping around in there.
Maybe I'll spend the Fourth in the Honda's floorboard.
It's funny, one of my other cars is a '99 Ford Exploder 4 X 4. There's so much wind noise and it shakes and rattles so much I would never notice a sound like the Accord is making. This Accord is just so quiet . . . except for this intermittent noise.
Thanks again,
EZ