Any Gearheads Out There?

Random Things Breaking On The Truck Again...

I'm hoping one of y'all knows the interior of a Ford engine compartment.

Anybody know what this gizmo is called? It's bolted onto the firewall to the right of the engine block, just above the brake cylinder. It's got what appears to be vacuum lines and some electrical doohickies attached.

It's making an annoying musical humming sound at random times, starting with a "C" and dropping to "A", then quitting altogether.

It's not throwing an engine code, and everything seems to be running OK, but it's kinda getting on my nerves.

Any help is appreciated!! Muchas Gracias!