Megaphone: Difference between revisions
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{{About|the amplification device|the chemical compound|Megaphone (molecule)|other uses}} |
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{{redirect|Bullhorn|the G.I. Joe character|Bullhorn (G.I. Joe)|the type of tree|Bullhorn Acacia}} |
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[[File:MOHAI - firefighter's speaking trumpet 01A.jpg|thumb|A late 19th-century speaking trumpet used by [[firefighter]]s.]] |
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[[File:HPIM0145 megaphone.jpg|thumb|A small sports megaphone for cheering at sporting events, next to a 3 in. cigarette lighter for scale]] |
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A '''megaphone''', '''speaking-trumpet''', '''bullhorn''', '''blowhorn''', or '''loudhailer''' is usually a portable or hand-held, cone-shaped [[horn (acoustic)|acoustic horn]] used to [[amplifier|amplify]] a person’s voice or other [[sound]]s and direct it in a given direction. The sound is introduced into the narrow end of the megaphone, by holding it up to the face and speaking into it, and the sound waves radiate out the wide end. A megaphone increases the volume of sound by increasing the [[acoustic impedance]] seen by the [[vocal cords]], [[impedance matching|matching]] the impedance of the vocal cords to the air, so that more sound power is radiated. It also serves to direct the sound waves in the direction the horn is pointing. It somewhat distorts the sound of the voice because the [[frequency response]] of the megaphone is greater at higher sound [[frequency|frequencies]]. |
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Since the 1960s the voice-powered ''acoustic megaphone'' described above has been replaced by the ''electric megaphone'', which uses electric power and a folded horn to [[amplifier|amplify]] the voice. |
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==History== |
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[[File:Codex canadensis, p. 14.jpg|thumb|upright|Page from the [[Codex canadensis]], by [[Louis Nicolas]], circa 1675 to 1682, showing a native North-American chief using a megaphone made of bark]] |
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The initial inventor of the speaking trumpet is a subject of historical controversy. There have been references to speakers in Ancient Greece (5th Century B.C.) wearing masks with cones protruding from the mouth in order to amplify their voices in theatres. <ref> Montgomery, Henry C (1959). "Amplification and High Fidelity in the Greek Theater". The Classical Journal. 54 (6): 242–245. JSTOR 3294133.</ref> Hellenic architects may have also consciously utilized acoustic physics in their design of theatre amphitheaters. |
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A drawing by [[Louis Nicolas]] ''(right)'' on page 14 of the [[Codex canadensis]], circa 1675 to 1682, shows a [[Native Americans in the United States|Native American]] chief named Iscouakité using a megaphone made of birch bark. The text of the illustration says that he is addressing his soldiers through a birch bark tube. |
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[[File:Fotothek df tg 0008336 Akustik ^ Schall ^ Sprachrohr ^ Ordensliteratur.jpg|thumb|Drawing by [[Athanasius Kircher]], 1684, shows man ''(left)'' using megaphone to communicate over distance]] |
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Both [[Samuel Morland]] and [[Athanasius Kircher]] have been credited with inventing megaphones around the same time in the 17th century. Morland, in a work published in 1655, wrote about his experimentation with different horns. His largest megaphone consisted of over 20 feet of copper tube and could reportedly project a person's voice a mile and a half.<ref>Mills, Mara. "When Mobile Communication Technologies Were New." Endeavour 33.4 (200111111: 141-47.</ref> |
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Twenty years earlier, Kircher described a device that could be used as both a megaphone and for "overhearing" people speaking outside a house. His coiled horn would be mounted into the side of a building, with a narrow end inside that could be either spoken into or listened to, and the wide mouth projecting through the outside wall. |
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Morland favored a straight, tube-shaped speaking device. Kircher’s horn, on the other hand, utilized a “cochleate” design, where the horn was twisted and coiled to make it more compact. |
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A later, [[papier-mache]] trumpet of special design was the Sengerphone.<ref>[http://www.musicweb-international.com/senger.htm Sengerphone-Y by Len Mullenger]</ref> |
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Additionally, in ruins of [[Tiwanaku]] are stones around the central place with holes shaped in megaphone's profile. Their purpose is today unknown, but as local guards can show, it is possible to amplify human voice as it is loud enough to hear it across large area. |
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The term ‘megaphone’ was first associated with [[Thomas Edison]]’s instrument 200 years later. In 1878, Edison developed a device similar to the speaking trumpet in hopes of benefiting the deaf and hard of hearing. His variation included three separate funnels lined up in a row. The two outer funnels, which were six feet and eight inches long, were made of paper and connected to a tube inserted in each ear. The middle funnel was similar to Morland’s speaking trumpet, but had a larger slot to insert a user’s mouth.<ref>Prescott, George B. Bell's Electric Speaking Telephone: Its Invention, Construction, Application, Modification, and History. New York: D. Appleton &, 1884.</ref> |
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With Edison’s megaphone, a low whisper could be heard a thousand feet away, while a normal tone of voice could be heard roughly two miles away. On the listening end, the receiver could hear a low whisper at a thousand feet away. However the apparatus was much too large to be portable, limiting its use. George Prescott wrote: “The principal drawback at present is the large size of the apparatus.” |
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Since the 1960s acoustic megaphones have generally been replaced by electric versions ''(below)'', although the cheap, light, rugged acoustic megaphone is still used in a few venues, like cheering at sporting events and [[cheerleading]], and by [[lifeguard]]s at pools and beaches where the moisture could damage the electronics of electric megaphones. |
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{{multiple image |
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| image1 = Bundesarchiv Bild 102-10044, Reichswehr-Manöver.jpg |
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| caption1 = German soldier using a megaphone to command troops, 1930 |
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| width1 = 107 |
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| image2 = "Getting em up" at U.S.Naval Training Camp, Seattle, Washington. Webster ^amp, Stevens. - NARA - 533698.tif |
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| caption2 = A sailor using a megaphone to amplify the sound of a [[bugle]] to wake recruits at an American training camp in 1947 |
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| width2 = 200 |
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| image3 = Bundesarchiv Bild 183-H0729-0035-001, Berlin, Freibad Pankow, Bademeister.jpg |
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| caption3 = German lifeguard with megaphone, 1969 |
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| image4 = Riverside Stompers - Wolfgang Straka 2007 e.jpg |
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| caption4 = [[Austrian people|Austrian]] jazz singer using megaphone, 2007 |
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}} |
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==Electric megaphone== |
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{{multiple image |
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| image1 = "Geração à Rasca" Demonstration.jpg |
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| image2 = Reflex loudspeaker animation 2.gif |
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| footer =''(left)'' Woman using a small handheld electric megaphone at a demonstration in Portugal. ''(right)'' Electric megaphones use a type of [[horn loudspeaker]] called a ''reflex'' or ''reentrant horn''. The sound waves travel in a zigzag path through concentric widening ducts ''(b, c, and d)''. |
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An electric megaphone is a handheld [[public address system]], an electronic device that amplifies the human voice like an acoustic megaphone, using electric power. It consists of a [[microphone]] to convert sound waves into an electrical [[audio signal]], an [[amplifier]] powered by a [[Battery (electricity)|battery]] to increase the power of the audio signal, and a [[loudspeaker]] to convert the audio signal to sound waves again. Although slightly heavier than acoustic megaphones, electric megaphones can amplify the voice to a higher level, to over 90 dB. They have replaced acoustic megaphones in most applications, and are generally used to address congregations of people wherever stationary public address systems are not available; at outdoor sporting events, [[movie set]]s, [[political rally|political rallies]], and [[street demonstration]]s. |
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Although electronic [[public address system]]s have existed since [[vacuum tube]] [[amplifier]]s were developed in the early 1920s, vacuum tube versions were too heavy to be portable. Practical portable electric megaphones had to await the development of [[microelectronics]] which followed the invention of the [[transistor]] in 1947. In 1954, TOA Corporation developed the EM-202, the world's first transistorized megaphone.<ref>[http://www.toa.jp/profile/history.html#1950s TOA Corporation Megaphone History]</ref> |
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Handheld versions are shaped generally like the old acoustic megaphone, with a microphone at one end and a [[horn speaker]] at the other, and a [[pistol grip]] on the side, with a trigger switch to turn it on. In use, the device is held up to the mouth, and the trigger is pressed to turn it on while speaking. Other larger versions hang from the shoulder on a strap, and have a separate handheld microphone on a cord to speak into, so users can address a crowd without the instrument obscuring their faces. A vast array of modern electric megaphones are available to purchase, and characteristics like power, weight, price, and the presence of alarms and shoulder straps all contribute to a consumer’s choice.<ref>[https://www.audiolinks.com/articles/choosingamegaphone/ "Megaphone & Bullhorns] {{webarchive|url=https://web.archive.org/web/20120901135751/https://www.audiolinks.com/articles/choosingamegaphone/ |date=2012-09-01 }}</ref> |
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The shape of the megaphone directly affects the range of projection; narrower horns compensate for lower power by concentrating sound more sharply than wide horns. |
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{{multiple image |
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| image1 = 電気メガホンEM-202.JPG |
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| caption1 = The EM-202 made by TOA Corp., the first transistorized handheld megaphone |
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| image2 = Seattle Hempfest 2007 - Dominic Holden.jpg |
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| caption2 = Waist-slung megaphones with separate microphones |
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| image3 = Knut Marius Gaarder.jpg |
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| caption3 = Man using megaphone with separate microphone |
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== Impact on society == |
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Portable megaphones are widely used for crowd management and mass communication. When needing to communicate information or directions to a large crowd of people in one place, an electric megaphone is valuable when other public address systems are not present. |
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Besides their practical implications, [[public address system]]s, including megaphones, also had a social impact. Public address systems helped promote women’s participation in society. In events like the National Republican and Democratic Conventions of 1920, when electronic [[public address system]]s were first becoming popularized, women used these amplifying technologies during roll call of participants.<ref>Kramarae, Cheris. ''Technology and Women's Voices: Keeping in Touch''. New York: [[Routledge & Kegan Paul]], 1988.</ref> Later, portable electric megaphones extended this equalizing influence to outdoor events. Some protest leaders use electric megaphones to speak to an outdoor crowd or to other protesters. |
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As of the 2010s, [[cheerleading]] is one of the few fields that still uses acoustic megaphones. [[Cheerleaders]] at the [[University of Minnesota]] are credited with first using acoustic megaphones in routines in 1898. Since then, cheerleaders have relied heavily on acoustic megaphones during performances at sporting events. Generally, female cheerleaders would use [[Pom-pon|pom poms]] while male cheerleaders, with loud booming voices, would project cheers through megaphones.<ref>Hanson, Mary Ellen. ''Go! Fight! Win!: Cheerleading in American Culture''. Bowling Green, OH: [[Bowling Green State University]] Popular, 1995.</ref> [[Vocal projection]] is an important aspect for cheerleading, so experts recommend the use of acoustic megaphones not only to increase the volume of sound, but also to protect performers’ voices in the process.<ref>Carrier, Justin, and Donna McKay. ''Complete Cheerleading''. Champaign, IL: [[Human Kinetics]], 2006.</ref> |
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[[File:David Wark Griffith - 1922 2.jpg|thumb|upright=0.7|Silent film director [[D. W. Griffith]] using megaphone in 1922.]] |
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For decades, film directors have used megaphones to communicate with their cast and crew on sets where it was hard to hear. The acoustic megaphone became an iconic clichéd symbol of a movie director, although modern directors use electric megaphones. A major contributor to this cliche was [[Cecil B. DeMille]], director of epic movies like [[The Ten Commandments (1956 film)|''The Ten Commandments'']] and [[The King of Kings (1927 film)|''The King of Kings'']]. Many of his films were biblical epics set on vast outdoor sets that required communication with hundreds of [[Extra (acting)|extras]].<ref>[https://www.imdb.com/name/nm0001124/bio IMDB: Cecil B. DeMille]</ref> |
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The distinctive distorted sound of a human voice amplified by a megaphone is widely recognized, from its use in train and bus stations and sports arenas. Applied to music, it gives the sound of an antique acoustic [[Phonograph|gramophone]] [[record player]]. It has been used in [[radio advertisement]]s and popular music to give retro and often humorous effects. A recorded voice or music can be processed to give it a "megaphone" sound effect without using an actual megaphone, by audio recording decks and software. In recording software like [[Logic Pro]] and [[Pro Tools]], selecting certain filters and settings will produce an artificial sound almost indistinguishable from an electric megaphone.<ref>{{cite news|url=http://smallbusiness.chron.com/megaphone-effect-radio-ads-32497.html|title=The Megaphone Effect in Radio Ads|last=Savage|first=Jason|work=[[Houston Chronicle]] / [[Demand Media]]|accessdate=2 September 2013}}</ref> |
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==Legal restrictions== |
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Governments can pass laws restricting the use of electronically amplified megaphones. In the US the ability to use a megaphone in public can be restricted to certain decibel levels, time of day or banned in residential neighborhoods. They however can't ban the kind of speech used with a megaphone.<ref>{{cite book|last1=Bernstein|first1=David. E.|title=You Can't Say That!: The Growing Threat to Civil Liberties from Antidiscrimination Laws|publisher=Cato Institute|page=31|edition=2003|accessdate=24 February 2018}}</ref> |
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==See also== |
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* [[Horn (acoustic)]] |
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* [[Horn loudspeaker]] |
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* [[Amplifier]] |
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* [[Microphone]] |
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* [[Long Range Acoustic Device]] |
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==References== |
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{{reflist}} |
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==External links== |
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*{{commons category inline|Megaphones}} |
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*[http://www.thefreelibrary.com/Controlling+public+protest%3a+First+Amendment+implications.-a016473804 ''Controlling Public Protest: First Amendment Implications''] An article about restrictions that may legally be imposed on public protests (including use of bullhorns), by Daniel L. Schofield, S.J.D., published in the November 1994 issue of the [[Federal Bureau of Investigation|FBI]]'s [[FBI Law Enforcement Bulletin|''Law Enforcement Bulletin'']]. |
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[[Category:Audio amplifiers]] |
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Revision as of 22:19, 17 September 2018
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