Editing Subwoofer (section)

===1920s to 1950s precursors===
From about 1900 to the 1950s, the "lowest frequency in practical use" in recordings, broadcasting and music playback was 100 Hz.<ref name="Fink" /> When sound was developed for motion pictures, the basic RCA sound system was a single 8-inch (20&nbsp;cm) speaker mounted in straight horn, an approach which was deemed unsatisfactory by Hollywood decisionmakers, who hired [[Western Electric]] engineers to develop a better speaker system.<ref name="Eargle2007" /> The early Western Electric experiments added a set of 18-inch drivers for the low end in a large, open-backed baffle (extending the range down to 40 Hz) and a high-frequency unit, but [[Metro-Goldwyn-Mayer|MGM]] was not pleased with the sound of the three-way system, as they had concerns about the delay between the different drivers.<ref name="Eargle2007" />

In 1933, the head of MGM's sound department, [[Douglas Shearer]], worked with [[John Kenneth Hilliard|John Hilliard]] and [[James B. Lansing]] (who would later found [[Altec Lansing]] in 1941 and [[JBL (company)|JBL]] in 1946) to develop a new speaker system that used a two-way enclosure with a W-shaped bass horn that could go as low as 40&nbsp;Hz.<ref name="Eargle2007" /> The Shearing-Lansing 500-A ended up being used in "screening rooms, dubbing theaters, and early sound reinforcement".<ref name="Eargle2007" /> In the late 1930s, Lansing created a smaller two-way speaker with a {{convert|15|in|cm|adj=on|sp=us}} woofer in a vented enclosure, which he called the Iconic system; it was used as a studio monitor and in high-end home hi-fi set-ups.<ref name="Eargle2007" />

During the 1940s [[swing era]], to get deeper bass, "pipelike opening[s]" were cut into speaker enclosures, creating [[bass reflex]] enclosures, as it was found that even a fairly inexpensive speaker enclosure, once modified in this way, could "transmit the driving power of a heavy...drumbeat—and sometimes not much else—to a crowded dancefloor."<ref name="Fink" /> Prior to the development of the first subwoofers, woofers were used to reproduce bass frequencies, usually with a crossover point set at 200 Hz and a {{convert|4|in|cm|adj=on|sp=us}} loudspeaker in an infinite baffle or in professional sound applications, a "hybrid horn-loaded" bass reflex enclosure (such as the 15-inch [[Altec Lansing]] A-7 enclosure nicknamed the "Voice of the Theater", which was introduced in 1946).<ref name="Hill2010" /> In the mid-1950s, the [[Academy of Motion Picture Arts and Sciences]] selected the "big, boxy" Altec A-7 as the industry standard for movie sound reproduction in theaters.<ref name=VoiceOfTheTheater />