Megaphone
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A megaphone, speaking-trumpet, bullhorn, blowhorn, or loudhailer is usually a portable or hand-held, cone-shaped
acoustic horn An acoustic horn or waveguide is a tapered sound guide designed to provide an acoustic impedance match between a sound source and free air. This has the effect of maximizing the efficiency with which sound waves from the particular source are tran ...
used to amplify a person's voice or other
sound In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the ...
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 Acoustic impedance and specific acoustic impedance are measures of the opposition that a system presents to the acoustic flow resulting from an acoustic pressure applied to the system. The SI unit of acoustic impedance is the pascal-second per cub ...
seen by the
vocal cords In humans, vocal cords, also known as vocal folds or voice reeds, are folds of throat tissues that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and vibrating for speech ...
, 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 In signal processing and electronics, the frequency response of a system is the quantitative measure of the magnitude and phase of the output as a function of input frequency. The frequency response is widely used in the design and analysis of sy ...
of the megaphone is greater at higher sound frequencies. Since the 1960s the voice-powered ''acoustic megaphone'' described above has been replaced by the ''electric megaphone'', which uses a
microphone A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public ...
, an electrically-powered amplifier and a folded
horn loudspeaker A horn loudspeaker is a loudspeaker or loudspeaker element which uses an horn (acoustic), acoustic horn to increase the overall efficiency of the driving element(s). A common form ''(right)'' consists of a compression driver which produces sound w ...
to amplify the voice.


History

The initial inventor of the speaking trumpet is a subject of historical controversy. There have been references to speakers in
Ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cult ...
(5th Century B.C.) wearing masks with cones protruding from the mouth in order to amplify their voices in theatres. Hellenic architects may have also consciously utilized acoustic physics in their design of theatre amphitheaters. A drawing by Louis Nicolas ''(right)'' on page 14 of the Codex canadensis, circa 1675 to 1682, shows a 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. Both
Samuel Morland Sir Samuel Morland, 1st Baronet (1625 – 30 December 1695), or Moreland, was an English academic, diplomat, spy, inventor and mathematician of the 17th century, a polymath credited with early developments in relation to computing, hydraulics a ...
and
Athanasius Kircher Athanasius Kircher (2 May 1602 – 27 November 1680) was a German Jesuit scholar and polymath who published around 40 major works, most notably in the fields of comparative religion, geology, and medicine. Kircher has been compared to fe ...
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. 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. 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. A later,
papier-mâché upright=1.3, Mardi Gras papier-mâché masks, Haiti upright=1.3, Papier-mâché Catrinas, traditional figures for day of the dead celebrations in Mexico Papier-mâché (, ; , literally "chewed paper") is a composite material consisting of p ...
trumpet of special design was the Sengerphone. Additionally, in ruins of
Tiwanaku Tiwanaku ( es, Tiahuanaco or ) is a Pre-Columbian archaeological site in western Bolivia near Lake Titicaca, about 70 kilometers from La Paz, and it is one of the largest sites in South America. Surface remains currently cover around 4 square kilo ...
are stones around the central place with holes shaped in a megaphone's profile. Their purpose is today unknown, but as local guards can show, it is possible to amplify a human voice loud enough to hear it across a large area. The term 'megaphone' was first associated with
Thomas Edison Thomas Alva Edison (February 11, 1847October 18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventio ...
'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. 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." Prior to the invention of the electric microphone, early pop singers sang with a megaphone. 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 Cheerleading is an activity in which the participants (called cheerleaders) cheer for their team as a form of encouragement. It can range from chanting slogans to intense physical activity. It can be performed to motivate sports teams, to ente ...
, and by
lifeguard A lifeguard is a rescuer who supervises the safety and rescue of swimmers, surfers, and other water sports participants such as in a swimming pool, water park, beach, spa, river and lake. Lifeguards are trained in swimming and CPR/ AED first a ...
s at pools and beaches where the moisture could damage the electronics of electric megaphones.


Electric megaphone

An electric megaphone is a handheld
public address system A public address system (or PA system) is an electronic system comprising microphones, amplifiers, loudspeakers, and related equipment. It increases the apparent volume (loudness) of a human voice, musical instrument, or other acoustic sound sou ...
, an electronic device that amplifies the human voice like an acoustic megaphone, using electric power. It consists of a
microphone A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public ...
to convert sound waves into an electrical
audio signal An audio signal is a representation of sound, typically using either a changing level of electrical voltage for analog signals, or a series of binary numbers for digital signals. Audio signals have frequencies in the audio frequency range of r ...
, an
amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It may increase the power significantly, or its main effect may be to boost the v ...
powered by a
battery Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...
to increase the power of the audio signal, and a
loudspeaker A loudspeaker (commonly referred to as a speaker or speaker driver) is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A ''speaker system'', also often simply referred to as a "speaker" or " ...
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 Set construction is the process undertaken by a construction manager to build full-scale scenery, as specified by a scenic design, production designer or art director working in collaboration with the theatre director, director of a productio ...
s, political rallies, and street demonstrations. Although electronic
public address system A public address system (or PA system) is an electronic system comprising microphones, amplifiers, loudspeakers, and related equipment. It increases the apparent volume (loudness) of a human voice, musical instrument, or other acoustic sound sou ...
s have existed since
vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type kn ...
amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It may increase the power significantly, or its main effect may be to boost the v ...
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 Microelectronics is a subfield of electronics. As the name suggests, microelectronics relates to the study and manufacture (or microfabrication) of very small electronic designs and components. Usually, but not always, this means micrometre-s ...
which followed the invention of the
transistor upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch e ...
in 1947. In 1954, TOA Corporation developed the EM-202, the world's first transistorized megaphone. Handheld versions are shaped generally like the old acoustic megaphone, with a microphone at one end and a
horn speaker A horn loudspeaker is a loudspeaker or loudspeaker element which uses an horn (acoustic), acoustic horn to increase the overall efficiency of the driving element(s). A common form ''(right)'' consists of a compression driver which produces sound w ...
at the other, and a
pistol grip On a firearm or other tools, a pistol grip is a distinctly protruded handle underneath the main mechanism, to be held by the user's hand at a more vertical (and thus more ergonomic) angle, similar to the how one would hold a conventional pist ...
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. 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.


Impact on society

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. Besides their practical implications,
public address system A public address system (or PA system) is an electronic system comprising microphones, amplifiers, loudspeakers, and related equipment. It increases the apparent volume (loudness) of a human voice, musical instrument, or other acoustic sound sou ...
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 A public address system (or PA system) is an electronic system comprising microphones, amplifiers, loudspeakers, and related equipment. It increases the apparent volume (loudness) of a human voice, musical instrument, or other acoustic sound sou ...
s were first becoming popularized, women used these amplifying technologies during roll call of participants. 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. As of the 2010s,
cheerleading Cheerleading is an activity in which the participants (called cheerleaders) cheer for their team as a form of encouragement. It can range from chanting slogans to intense physical activity. It can be performed to motivate sports teams, to ente ...
is one of the few fields that still uses acoustic megaphones.
Cheerleaders Cheerleading is an activity in which the participants (called cheerleaders) cheer for their team as a form of encouragement. It can range from chanting slogans to intense physical activity. It can be performed to motivate sports teams, to ente ...
at the
University of Minnesota The University of Minnesota, formally the University of Minnesota, Twin Cities, (UMN Twin Cities, the U of M, or Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Tw ...
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 poms A pom-pom – also spelled pom-pon, pompom or pompon – is a decorative ball or tuft of fibrous material. The term may refer to large tufts used by cheerleaders, or a small, tighter ball attached to the top of a hat, also known as a ...
while male cheerleaders, with loud booming voices, would project cheers through megaphones.
Vocal projection Voice projection is the strength of speaking or singing whereby the human voice is used powerfully and clearly. It is a technique employed to command respect and attention, as when a teacher talks to a class, or simply to be heard clearly, as used ...
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. 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 Cecil Blount DeMille (; August 12, 1881January 21, 1959) was an American film director, producer and actor. Between 1914 and 1958, he made 70 features, both silent and sound films. He is acknowledged as a founding father of the American cine ...
, director of epic movies like ''The Ten Commandments'' and ''The King of Kings''. Many of his films were biblical epics set on vast outdoor sets that required communication with hundreds of extras. 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 gramophone
record player A phonograph, in its later forms also called a gramophone (as a trademark since 1887, as a generic name in the UK since 1910) or since the 1940s called a record player, or more recently a turntable, is a device for the mechanical and analogu ...
. It has been used in
radio advertisement In the United States, commercial radio stations make most of their revenue by selling airtime to be used for running radio advertisements. These advertisements are the result of a business or a service providing a valuable consideration, usually ...
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 Logic Pro is a digital audio workstation (DAW) and MIDI music sequencer, sequencer software application for the macOS platform. It was originally created in the early 1990s as Notator Logic, or Logic, by German software developer C-Lab which ...
and
Pro Tools Pro Tools is a digital audio workstation (DAW) developed and released by Avid Technology (formerly Digidesign) for Microsoft Windows and macOS. It is used for music creation and production, sound for picture (sound design, audio post-productio ...
, selecting certain filters and settings will produce an artificial sound almost indistinguishable from an electric megaphone.


Legal restrictions

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. However, under the
First Amendment First or 1st is the ordinal form of the number one (#1). First or 1st may also refer to: *World record, specifically the first instance of a particular achievement Arts and media Music * 1$T, American rapper, singer-songwriter, DJ, and rec ...
, the specific kinds of speech used with a megaphone cannot be restricted.


See also

*
Long range acoustic device A long-range acoustic device (LRAD) is an acoustic hailing device (AHD), sound cannon and sonic weapon developed by Genasys. It has been used as a method of crowd control, which has caused permanent hearing damage, having an extremely high ...
(LRAD) *
Water Talkie Water Talkies are devices which makes talking underwater possible. They were invented by Richie Stachowski, Jr. in 1995 at age 11. The Water Talkie is a colorful, cone-shaped device that amplifies voices underwater for up to . What started as on ...
*
Human microphone A human microphone, also known as the people's microphone, is a means for delivering a speech to a large group of people, wherein persons gathered around the speaker repeat what the speaker says, thus "amplifying" the voice of the speaker without ...


References


External links


"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
FBI The Federal Bureau of Investigation (FBI) is the domestic Intelligence agency, intelligence and Security agency, security service of the United States and its principal Federal law enforcement in the United States, federal law enforcement age ...
's ''Law Enforcement Bulletin''. {{Authority control Audio amplifiers