No, the term really means only one thing. Neither the 9" nor the 11" slant-6 1bbl air cleaner is an unsilenced design. Both are designed to silence air intake noise. There was an unsilenced air cleaner used only in 1962, only on the 170 engine, but it didn't share any components with these we're talking about. You can make an unsilenced air cleaner by using the base and bail from the 9" air cleaner and the lid from the 11" unit. That's the setup I was too busy listening to the roar from when I got stopped by a traffic cop for the very first time -- a lot of years ago on my way to high school.