Megaphone
A megaphone (from the Greek megas "big" and fone "voice"), In some countries it is also known as speaker; It is usually a cone-shaped portable or hand-held acoustic speaker used to amplify a person's voice or other sounds and direct it in a certain direction. Sound is input into the narrow end of the megaphone by holding it up to your face and speaking into it, and sound waves radiate out of the wide end. A megaphone increases the volume of sound by increasing the acoustic impedance seen by the vocal folds, matching the impedance of the vocal folds to the air, so that more sound power is radiated. It also serves to direct sound waves in the direction the speaker is pointing. It somewhat distorts the sound of the voice because the frequency response 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Since the 1960s, the voice-powered acoustic megaphone described above has been replaced by the electric megaphone, which uses a microphone, an electric amplifier, and a folded horn speaker to amplify the voice.
History
The initial inventor of the megaphone is a subject of historical controversy. There have been references to speakers in ancient Greece (5th century BC) wearing masks with cones protruding from the mouth to amplify their voices in theaters. Hellenic architects may also have consciously used acoustic physics in their design of theater 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 in the illustration says that he addresses the soldiers through said instrument.
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 more than 20 feet of copper tubing 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 a megaphone and to "listen" to people who talk outside the house. His coiled horn would be mounted on the side of a building, with a narrow end on the inside through which one could speak or listen, and the wide mouth projecting through the outside wall.
Morland favored a straight, tube-shaped speaking device. Kircher's horn, on the other hand, used a 'cochleato' design, where the horn was twisted and rolled to make it more compact.
A specially designed paper mache trumpet was the Sengerphone.
Also, in the ruins of Tiahuanaco there are stones around the central place with holes in the profile of the megaphone. Today its purpose is unknown, but as local guards can show, it is possible to amplify the human voice as it is loud enough to be heard over a large area.
The term "megaphone" It was first associated with Thomas Edison's instrument 200 years later. In 1878, Edison developed a trumpet-like speaking device 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 eight inches long, were made of paper and connected to a tube inserted into each ear. The central funnel was similar to the Morland 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 about two miles away. At the listening end, the receiver could hear a low whisper from a thousand feet away. However, the device was too large to be portable, which limited its use. George Prescott wrote: "The main drawback at the present time is the large size of the apparatus."
Since the 1960s, acoustic megaphones have generally been replaced by electric versions (below), although the cheap, lightweight, heavy-duty acoustic megaphone is still used in some venues, such as cheering at events sports and cheerleaders, and by lifeguards at pools and beaches where humidity could damage the electronics of electric megaphones.
Electric megaphone
An electric megaphone is a portable public address system, an electronic device that amplifies the human voice like an acoustic megaphone, using electrical energy. It consists of a microphone to convert sound waves into an electrical audio signal, a battery-powered amplifier to increase the power of the audio signal, and a speaker to convert the audio signal into sound waves again. Although slightly heavier than acoustic megaphones, electric megaphones can amplify voice to a higher level, over 90 dB. They have replaced acoustic megaphones in most applications, and are generally used to address congregations of people where fixed public address systems are not available; at outdoor sporting events, movie sets, political rallies and street demonstrations.
Although electronic public address systems have existed since the development of loudspeaker amplifiers, vacuum tubes In the early 1920s, vacuum tube versions were too heavy to be portable. Practical portable electric megaphones had to await the development of microelectronics that followed the invention of the transistor in 1947. In 1954, TOA Corporation developed the EM-202, the world's first transistorized megaphone.
Handheld versions are generally shaped 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 talking. Other larger versions hang over the shoulder with a strap and have a separate handheld microphone with a speaking cable, so users can address a crowd without the instrument obscuring their faces. A wide range of modern electric megaphones can be purchased, and features such as power, weight, price, and the presence of alarms and shoulder straps contribute to consumer choice.
The shape of the megaphone directly affects the projection range; Narrower speakers compensate for lower power by focusing the sound more sharply than wide speakers.
Impact on society
Portable megaphones are widely used for crowd management and mass communication. When information or instructions need to be communicated to a large crowd of people in a single location, an electric megaphone is valuable when other public address systems are not available.
In addition to their practical implications, public address systems, including megaphones, also had a social impact. Public address systems helped promote women's participation in society. At events such as the 1920 National Republican and Democratic Conventions, when electronic public address systems first became popular, women used these amplification technologies during roll call. Later, portable electric megaphones extended this equalizing influence to outdoor events. Some protest leaders use electric megaphones to speak to an outdoor crowd or other protesters.
As of the 2010s, cheerleading is one of the few fields that still uses acoustic megaphones. The University of Minnesota cheerleaders are credited with the first use of 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, while male cheerleaders, with loud, loud voices, would project cheers through megaphones. Vocal projection is an important aspect for cheerleaders, which is why experts recommend the use of acoustic megaphones. not only to increase the volume of the sound, but also to protect the performers' voices in the process.
For decades, film directors have used megaphones to communicate with their cast and crew on sets where it was difficult to hear them. The acoustic megaphone became a clichéd iconic symbol of a film director, although modern directors use electric megaphones. One of the main contributors to this cliché was Cecil B. DeMille, director of epic films such as The Ten Commandments and The King of Kings. Many of his films were biblical epics set on vast outdoor stages that required communication with hundreds of extras.
The distinctive distorted sound of a human voice amplified by a megaphone is widely recognized for its use in train and bus stations and sports stadiums. Applied to music, it gives the sound of an old acoustic record player. It has been used in radio advertisements 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 a real megaphone, through audio recording platforms and software. In recording software such as Logic Pro and Pro Tools, 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 United States, the ability to use a megaphone in public may be restricted to certain decibel levels, time of day, or prohibited in residential neighborhoods. However, under the First Amendment, the specific types of speech used with a megaphone cannot be restricted.