Shutter?

[L. Bird]

Maybe he really means "shutter."  See number 2 there, from dictionary.com:

1. One that shuts, as:
a. A hinged cover or screen for a window, usually fitted with louvers.
b. A mechanical device of a camera that controls the duration of a 
photographic exposure, as by opening and closing to allow light coming 
through the lens to expose a plate or film.

2. shutters Music. The movable louvers on a pipe organ, controlled by 
pedals, that open and close the swell box.