Editing Loudspeaker (section)

===First loudspeaker systems===
In the 1930s, loudspeaker manufacturers began to combine two and three drivers or sets of drivers each optimized for a different frequency range in order to improve frequency response and increase sound pressure level.<ref>{{Cite book |last1=Spanias |first1=Andreas |last2=Painter |first2=Ted |last3=Atti |first3=Venkatraman |date=2007 |title=Audio Signal Processing and Coding |publisher=Wiley-Interscience |isbn=978-0-470-04196-3 |url=https://books.google.com/books?id=J7_nVWzx1Q4C }}</ref> In 1937, the first film industry-standard loudspeaker system, "The Shearer Horn System for Theatres",<ref>{{Cite web |url=http://www.lansingheritage.org/images/lmco/bulletins/2b.jpg |title=Lansingheritage.com: (1937 brochure image) ''The Shearer Horn System for Theatres'' |access-date=August 30, 2024 }}</ref> a two-way system, was introduced by [[Metro-Goldwyn-Mayer]]. It used four 15" low-frequency drivers, a crossover network set for 375&nbsp;[[Hertz|Hz]], and a single multi-cellular horn with two compression drivers providing the high frequencies. [[John Kenneth Hilliard]], [[James Bullough Lansing]], and [[Douglas Shearer]] all played roles in creating the system. At the [[1939 New York World's Fair]], a very large two-way public address system was mounted on a tower at [[Flushing Meadows]]. The eight 27" low-frequency drivers were designed by [[Rudy Bozak]] in his role as chief engineer for Cinaudagraph. High-frequency drivers were likely made by [[Western Electric]].<ref>{{cite magazine |last=Bozak |first=R.T. |date=June 1940 |title= |magazine=Electronics }}{{Title missing|date=July 2024}}</ref>

[[Altec Lansing]] introduced the ''604'', which became their most famous coaxial [[Altec Lansing Duplex|Duplex]] driver, in 1943. It incorporated a high-frequency horn that sent sound through a hole in the pole piece of a 15-inch woofer for near-point-source performance.<ref>{{Cite web |url=http://www.lansingheritage.org/images/altec/catalogs/1943/page05.jpg |title=Lansing Heritage. ''Loudspeakers by Lansing: First Time in History. A Two-Way Loud Speaker in Compact Form.'' (1943 catalog image) }}</ref> Altec's "Voice of the Theatre" loudspeaker system was first sold in 1945, offering better coherence and clarity at the high output levels necessary in movie theaters.<ref>{{Cite web |url=http://www.lansingheritage.org/images/altec/catalogs/1966-vott/page2.jpg |title=Lansing Heritage. ''1966 Voice of the Theatre'' (catalog image) }}</ref> The Academy of Motion Picture Arts and Sciences immediately began testing its sonic characteristics; they made it the [[Cinema (place)|film house]] industry standard in 1955.<ref>{{cite web |url=http://www.audioheritage.org/html/people/hilliard.htm |title=Biography of John Hilliard |website=AudioHeritage.org |access-date=May 6, 2009 }}</ref>

In 1954, [[Edgar Villchur]] developed the [[acoustic suspension]] principle of loudspeaker design. This allowed for better bass response than previously obtainable from drivers mounted in larger cabinets.<ref>{{cite magazine |last=Villchur |first=Edgar |date=1954 |title=Revolutionary Loudspeaker and Enclosure |issue=October |publisher=Audio Engineering |url=https://worldradiohistory.com/Archive-All-Audio/Archive-Audio/50s/Audio-1954-Oct.pdf |page=25 |access-date=August 30, 2024 }}</ref>  He and his partner [[Henry Kloss]] formed the [[Acoustic Research]] company to manufacture and market speaker systems using this principle.<ref>{{cite web |url=http://www.aes.org/aeshc/jaes.obit/JAES_V59_12_PG1004.pdf |title=Edgar M. Villchur 1917-2011 |publisher=[[Audio Engineering Society]] |access-date=October 12, 2021 }}</ref>  Subsequently, continuous developments in enclosure design and materials led to significant audible improvements.<ref>{{Cite web |title=The History Of Acoustic Research / AR |url=https://auralfetish.com/pages/acoustic-research |website=Aural HiFi |access-date=April 18, 2022 }}</ref>

The most notable improvements to date in modern dynamic drivers, and the loudspeakers that employ them, are improvements in cone materials, the introduction of higher-temperature adhesives, improved permanent [[magnet]] materials, improved measurement techniques, [[computer-aided design]], and finite element analysis. At low frequencies, [[Thiele/Small parameters]] electrical network theory has been used to optimize bass driver and enclosure [[synergy]] since the early 1970s.<ref>{{cite journal |last=Small |first=R.H. |date=1972 |title=Direct Radiator Loudspeaker System Analysis |journal=Journal of the Audio Engineering Society |volume=20 |issue=June |pages=383–395 }}</ref>
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