A loudspeaker also called speaker driver or most frequently just speaker is an electroacoustic transducer, that is, a device that converts an electrical audio signal into a corresponding sound.
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
Speakers contain many components, including a frame, a magnet, an iron core, a voice coil, and a cone. The magnet and the cone are attached to the frame. The voice coil is an insulated wire wrapped around a bobbin and connected to the audio source. The bobbin is attached to the cone and contains a soft iron core.
When the voice coil receives an audio signal, it moves back and forth to vibrate the cone, which produces sound. The cone is often made from plastic, paper, aluminum, fiber, or rubber. The speaker may sit in an
enclosure made from MDF board.
The very first form of loudspeaker came to be when telephone systems were developed in the late 1800s.
Johann Philipp Reis installed an electric loudspeaker in his telephone in 1861 and it could reproduce clear tones as well as reproduce muffled speech.
Alexander Graham Bell patented his first electric loudspeaker capable of reproducing intelligible speech in 1876 as part of his telephone. Ernst Siemens improved upon it the following year.
In 1898, Horace Short earned a patent for a loudspeaker driven by compressed air. A few companies produced record players using compressed-air loudspeakers, but these designs had poor sound quality and could no reproduce sound at a low volume.
But it was in 1912 that loudspeakers really became practical – due in part to electronic amplification by a vacuum tube.
By the 1920s, they were used in radios, phonographs, public address systems and theater sound systems for talking motion pictures.
The most common type of loudspeaker today is the dynamic speaker. It was invented in 1925 by Edward W. Kellogg and Chester W. Rice issued as US Patent 1,707,570. Apr 2, 1929.
In the 1930s, loudspeaker manufacturers began to combine two and three drivers or sets of drivers each optimized for a different frequency range in order to improve frequency response and increase sound pressure level.
In 1937, the first film industry-standard loudspeaker system, “The Shearer Horn System for Theatres”, a two-way system, was introduced by Metro-Goldwyn-Mayer.
At the 1939 New York World’s Fair, a very large two-way public address system was mounted on a tower at Flushing Meadows.
Altec Lansing introduced the 604, which became their most famous coaxial Duplex driver, in 1943. It incorporated a high-frequency horn that sent sound through a hole in the pole piece of a 15-inch woofer for near-point-source performance. Altec’s “Voice of the Theatre” loudspeaker system was first sold in 1945, offering better coherence and clarity at the high output levels necessary in movie theaters.
In 1954, Edgar Villchur developed the acoustic suspension principle of loudspeaker design in Cambridge, Massachusetts. This allowed for better bass response than previously from drivers mounted in smaller cabinets which was important during the transition to stereo recording and reproduction.
In the older times, the computers had onboard speakers built into the chassis when they were initially released. These speakers were able to generate a series of different beeps and tones. In 1981, IBM released the first internal computer speaker, which produced basic low-quality sound.
Subsequently, continuous developments in enclosure design and materials led to significant audible improvements. The most notable improvements in modern speakers are improvements in cone materials, the introduction of higher-temperature adhesives, improved permanent magnet materials, improved measurement techniques, computer-aided design, and finite element analysis.
The most expensive speakers in the world -The Acapella Spharon Excalibur speakers cost $325,000 (£186,000) and can be fitted into living rooms having a minimum size of 40 m² (131 ft²) and consist of two pillars with four large 15 in (38 cm) woofers on each unit. Product Specifications: Efficiency: 100 dB/1W/1m Power handling: 100 watts (Peak handling of 1000 watts at 10 ms with no distortion) Recommended power output of the amplifier from: 15 watts Dimensions: 90.5 in x 59 in x 51.2 in (HxWxD) Weight: 1364 lb per speaker.
The Reverberant Acoustic Test Facility is a concrete-walled room and the loudest room in the world. It measures 57 ft (17.36 m) high, 47.5 ft (14.47 m) long, and 37.5 ft (11.43 m) wide. It has 36 massive loudspeaker horns (properly called “noise sources”) covering one entire wall. These speakers, driven by pressurised nitrogen gas, can saturate the room with 163 dB of continuous noise for up to 10 minutes.