Edgar Villchur, who along with partner Henry Kloss founded Acoustic Research, is generally credited with inventing bookshelf speakers.
[2] Villchur's key innovation was an acoustic suspension (also called "sealed box") design, by which the woofer and other drivers were in separately enclosed chambers.
[2] The acoustic suspension design enabled the air in the sealed box to act like a spring, to help prevent excessive excursion.
Technical improvements and less expensive mass-production technologies have made high-quality bookshelf speakers affordable for most audio enthusiasts.
Human perception of low-frequency sound is relatively non-directional, so a single subwoofer cabinet placed anywhere in the room (even hidden behind a sofa) is usually sufficient and may be placed anywhere.