Abstract:

The history of the dynamic speaker, a speaker in which the signal is applied to a voice coil that is part of the moving system, begins with the Rice and Kellog paper [Trans. AIEE 44, 461--475 (1925)] and the ``Radiola'' loudspeaker of 1926. Innovations since then include the ported or bass reflex enclosure of Thuras, patented in 1932, and the acoustic suspension system. (The author received a patent for the latter in 1956, but a court later ruled that is had been anticipated by prior art.) Present design practice often departs, for good or ill---in the author's opinion, mostly for ill---from design approaches of the past. For example, some current designs are aimed at creating directional sound rather than wide dispersion; some designs are aimed at controlling phase; and there is an explosion of design meant to influence loudspeaker performance through accessories such as speaker cables and speaker stands.