Megaphone

For other uses, see Megaphone (disambiguation).

"Bullhorn" redirects here. For the G.I. Joe character, see Bullhorn (G.I. Joe). For the type of tree, see Bullhorn Acacia.

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

Though some instrument of the kind appears to have been in earlier use, the origin of the megaphone, or speaking trumpet as it was called, is connected with the name of Athanasius Kircher and that of Sir Samuel Morland, who in 1670 proposed to the Royal Society of London the question of the best form for a speaking trumpet. Johann Heinrich Lambert, in the Berlin Memoirs for 1763, seems to have been the first to give a theory of the action of this instrument, based on an altogether imaginary analogy with the behaviour of light.^[2]

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

The first such device with the name Megaphone was an invention of Thomas Edison.^[4][5]

Electric megaphones

In 1954, TOA Corporation developed the EM-202, the world's first electric megaphone.^[6]

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.

See also

• Horn (acoustic)
• Horn loudspeaker

References

1. ^ See Example 1 of Impedance Matching for description of amplification mechanism
2. ^  Chisholm, Hugh, ed (1911). "Trumpet, Speaking and Hearing". Encyclopædia Britannica (11th ed.). Cambridge University Press. 
3. ^ Sengerphone-Y by Len Mullenger
4. ^ [1]
5. ^ [2]
6. ^ TOA Corporation Megaphone History

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's Law Enforcement Bulletin.

This sound technology article is a stub. You can help Wikipedia by expanding it.v · Categories: Audio amplifiers Sound technology stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем написать курсовую Military-industrial complex Type X Look at other dictionaries: mégaphone — [ megafɔn ] n. m. • 1886; de méga et phone, par l angl. ♦ Appareil portatif servant à amplifier la voix. ⇒ porte voix. ● mégaphone nom masculin Pavillon à évasement conique ou parabolique qui, placé devant la bouche, dirige les sons de parole… …   Encyclopédie Universelle Megaphone — Mégaphone Un mégaphone (de megas, grand et de phonê, voix) est un ustensile servant à amplifier la voix, appareil portatif composé d un pavillon, d un micro et d une poignée, ce dispositif fonctionne à pile. Il existe de nombreux modèles, la… …   Wikipédia en Français megaphone — ☆ megaphone [meg′ə fōn΄ ] n. [ MEGA + PHONE] a large, funnel shaped device for increasing the volume of the voice and directing it vt., vi. megaphoned, megaphoning to magnify or direct (the voice) with or as with a megaphone megaphonic… …   English World dictionary Megaphone — Meg a*phone, n. [Mega + Gr. fwnh voice.] A device to magnify sound, or direct it in a given direction in a greater volume, as a very large funnel used as an ear trumpet or as a speaking trumpet. [1913 Webster] …   The Collaborative International Dictionary of English megaphone — (n.) 1878, coined (perhaps by Thomas Edison, who invented it) from Gk. megas great (see MEGA (Cf. mega )) + phone voice (see FAME (Cf. fame) (n.)). Related: Megaphonic. In Greek, megalophonia meant grandiloquence, megalophonos loud voiced …   Etymology dictionary megaphone — ► NOUN ▪ a large cone shaped device for amplifying and directing the voice …   English terms dictionary Mégaphone —  Pour l’article homophone, voir Mégafaune. Un mégaphone. Un mégaphone (de megas, grand et de phonê, voix) est un ustensile servant à amplifier la voix, appareil portatif composé d un pavillon …   Wikipédia en Français megaphone — I. noun Date: 1878 a cone shaped device used to intensify or direct the voice • megaphonic adjective II. verb Date: 1901 transitive verb to transmit or address through or as if through a megaphone intransitive verb to speak through or as if… …   New Collegiate Dictionary megaphone — n. (to speak) through a megaphone * * * (to speak) through a megaphone …   Combinatory dictionary megaphone — UK [ˈmeɡəˌfəʊn] / US [ˈmeɡəˌfoʊn] noun [countable] Word forms megaphone : singular megaphone plural megaphones a piece of equipment used for making your voice louder when you are talking to a crowd …   English dictionary 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”