Megaphone

A mouthpiece (formerly referred to as voice tube or speaking tube ) is a device that directs the propagation of sound and thus in particular speech improves the intelligibility even at a greater distance of the listener from the speaker.

Basically, two types can be distinguished: the open and the closed mouthpiece.

Open mouthpiece ( megaphone )

The open mouthpiece, nowadays commonly referred to as megaphone or bullhorn and colloquially funny as a megaphone, is a funnel-shaped shell that is often made of sheet metal. The speaker assumes the smaller of the two openings in front of his mouth while he turns the greater the listeners.

The idea was to open mouthpiece as " speaking trumpet " in 1670 by the Englishman Samuel Morland, who made the first glass, iron or copper, and it used a cone-shaped funnel. Morland obviously knew that his chosen form would direct the sound propagation is not yet optimal. Therefore, he urged other scientists to develop better forms. This was even more random Laurent Cassegrain in 1672, the (initially for aesthetic reasons ) gave the funnel a hyperbolic shape and thereby found that this greatly improved the effectiveness.

A theory of the mouthpiece presented for the first time Johann Heinrich Lambert in the 18th century. Characterized it has been demonstrated that the hyperbolic shape is optimum, for which reason it is almost exclusively used in modern megaphone.

Bullhorn

Modern megaphones have usually via an electric voice amplifier consisting of a microphone, an amplifier and a speaker behind the actual mouthpiece is set. The efficiency is higher than conventional speakers, but with a much higher distortion with greater than 10 %. In mobile, battery-powered versions mostly used as the purely acoustic precursor. In Germany, the output power of mobile megaphones is limited to 120 dB in order to avoid hearing damage to bystanders. In the much more common stationary version, eg on railway platforms, provide Megaphone is looking speakers whose frequency characteristic is in contrast to, for example, concert music boxes optimized for speech. Modern Hand Megaphone also often offer completely new opportunities, they have built-in siren signal generator or are able to produce melodies. Thus, a fast and enjoyable for the audience attention attainment can be achieved without having to rely directly on the human voice.

Closed mouthpiece

When closed mouthpiece (also communication pipe ), the pipe is not funnel-shaped, but the entire length equidistant. In contrast to the open mouthpiece of the pipe must until shortly before the hearing of the listener's rich, so closed mouthpieces are usually much longer. Mostly they are used to connect two distant rooms directly with each other, thus enabling the means of submission of spoken words. With a 950 m long pipe you can still hear quiet sounds. These mouthpieces are used on ships to ensure a technically simple and safe even in an emergency voice communications between the major points (eg, bridge and engine room ). There are for this purpose today, though telephones that operate without an external power supply.

Metaphorical meaning

In a figurative sense, a mouthpiece is an organ, such as a newspaper, which represents the opinions and desires of a person or group to the outside. The term is sometimes used also critical for those who uncritically and unthinkingly reflect the views of another ( " JMDS. Mouthpiece be ").