Definição e significado de megaphone

  A late 19th-century speaking trumpet.

  An electronic megaphone.

A megaphone, speaking-trumpet, bullhorn, blowhorn, or loud hailer is a portable, usually hand-held, cone-shaped horn used to amplify a person’s voice or other sounds towards a targeted direction. This is accomplished by channelling the sound through the megaphone, which also serves to match the acoustic impedance of the voice cords to the air. The natural human voice tends to spread evenly in all directions, whereas when it is sent through a megaphone, the sound is concentrated in a given direction and the coupling of its energy to the air optimised,^[1] while if a listener is to the side, it is more difficult to hear what is being said.

  History

The initial inventor of the speaking trumpet is a subject of historical controversy, as both Samuel Morland and Athanasius Kircher lay claim to the device. Morland, in a work published in 1655, wrote about his experimentation with different horns and his most successful variant. This loudest horn was made of over 20 feet of copper and could supposedly project vocalizations as far as a mile and a half. ^[2]

Twenty years earlier, Kircher described a device that could be used for both broadcasting on one end and “overhearing” on the other. His coiled horn would be wedged into the side of a building, connecting a speaker or listener inside with the surrounding environment.

Morland favored a straight, tube-shaped speaking device, where an initial sound would reverberate in waves through the instrument and gradually become louder. Kircher’s horn, on the other hand, utilized a “cochleate” design, where the horn was twisted and coiled, unlike Morland’s design.

A later, papier-mache trumpet of special design was the Sengerphone.^[3]

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. ^[4]

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. The size of the instrument, as one researcher noted, was too large. George Prescott wrote: “The principal drawback at present is the large size of the apparatus.”

  Electric megaphones

In 1954, TOA Corporation developed the EM-202, the world's first transistorized megaphone.^[5]

An electronic megaphone amplifies sound to a higher decibel level. It can be amplified from over 90 dB. It consists of a microphone, an amplifier and a loudspeaker. Common uses for megaphones are at sporting events, political functions, and generally when one needs to address congregations of people in open spaces.

A vast array of modern electric megaphones are available to purchase, and characteristics like wattage, weight, price, and the presence of alarms and shoulder straps all contribute to a consumer’s choice. ^[6]

The shape of the megaphone directly affects the range of projection; narrower horns compensate lower wattage by concentrating sound much sharper than wide horns. Some megaphones even include a detachable microphone, so speakers can address a crowd without the instrument obscuring their face.

  Megaphone use

Besides its practical implications, the megaphone also had a social impact on society. The megaphone, along with other amplifying technologies like microphones and loudspeakers, helped promote women’s participation in society. In events like the National Republican and Democratic Conventions of 1920, when the electric megaphone was first becoming popularized, women utilized these amplifying technologies during roll call of participants. ^[7]

Portable megaphones are widely used for crowd management and mass communication. When needing to transmit important information or to guide a large amount of people, an electric megaphone is valuable if other public announcement devices are not present.

Cheerleaders at the University of Minnesota are credited with first implementing megaphones into routines in 1898. Since then, cheerleaders have relied heavily on acoustic megaphones during performances at sporting events. Generally, female cheerleaders would use pom pons while male cheerleaders, with loud booming voices, would project cheers through megaphones. ^[8] 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. ^[9]

For decades, film directors have used electric megaphones to communicate with their cast and crew on sets where it was hard to hear. Cecil B. DeMille, director of epic movies like The Ten Commandments and The King of Kings, was the first director to use a megaphone during production. Many of his films were biblical epics set in vast open spaces that required communication across hundreds of feet. ^[10]

In many modern radio ads, producers look to utilize a ‘megaphone effect’ without actually recording the instrument. In doing so, they digitize the recognizable characteristics of the electric megaphone and try to reproduce the qualities of distortion. On recording software like Logic and Pro Tools, selecting certain filters and settings will produce an artificial sound almost indistinguishable from an electric megaphone. ^[11]

  See also

• Horn (acoustic)
• Horn loudspeaker
• Amplifier
• Microphone

  References

  External links

Wikimedia Commons has media related to: Megaphones

• 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's Law Enforcement Bulletin.

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