The Evolution of Audio Speakers

the evolution of audio speakers v1Have you ever thought about what the world would be like if audio speakers, which are also known as loud speakers, were never invented? Sure, there would probably be no Justin Bieber or One Direction songs to listen to on the radio, because there would be no such thing as a radio. Neither would you have a television, or a phone, for that matter. You might not have given it any thought before you stumbled upon this article, but your life – along with everyone else’s – would be so different today without speakers. So how did these incredible sound boxes come into being?

A Sound History of Audio Speakers

The modern speaker traces its origins to as far back as 1861, when German scientist and inventor Johann Philipp Reis installed an electric loudspeaker in a telephone prototype that he was developing. Fifteen years later, Alexander Graham Bell patented his first electric loudspeaker which, unlike Reis’s, was capable of reproducing intelligible speech as part of the telephone that he was inventing. In 1877, Bell’s design became the inspiration for the creation of an improved electric loudspeaker by another noted German scientist, Ernst Siemens. At the time, loudspeakers were driven by compressed air, which moved a thin vibrating membrane across a metal horn. Sound quality was poor, and amplification was almost impossible at low volume.

The first loudspeaker to be driven by a moving coil – commonly known today as dynamic loudspeakers – was invented by a British physicist named Oliver Lodge in 1898. But it wasn’t until Danish engineer Peter Jensen and his business partner, Edwin Pridham, worked together in 1915 that the first practical dynamic audio speakers were invented.

By 1924, the dynamic loudspeaker had been significantly improved, becoming more similar to the products you see today. The patent for the moving coil direct radiator cone loudspeaker, which became the prominent basis for the technology being used today, was awarded to General Electric researchers, Chester Rice and Edward Kellogg. Their loudspeakers were first sold in 1926, and were marketed under the brand “Radiola”. The Rice and Kellogg Radiola loudspeakers were far superior – and understandably more popular – than the earlier products available then because of their ability to lower audio distortion and enhance sound quality. This resulted in a remarkably improved listening experience on the part of the consumers.

Developing Technology

During the Great Depression of 1930’s, consumer audio appeared to be headed towards obsolescence. The competition between manufacturers resulted in the development of multi-driver audio speakers that offered a better frequency response and improved sound pressure levels. In 1937, Metro-Goldwyn-Mayer introduced the Shearer Horn, which became the first two-way loudspeaker system that was designed for use in the film industry. Two years later, during the 1939 New York World’s Fair, visitors heard public address messages through a massive two-way loudspeaker system mounted on a tower atop Flushing Meadows. It consisted of eight 27-inch low-frequency drivers, and was designed by noted audio electronics and acoustics designer and engineer Rudolph Bozak. He was the Chief Engineer for American speaker company Cinaudagraph.

Consumer audio went through a dramatic resurgence just before the end of World War II, as people began to see the advantages of choosing electric loudspeakers over their old Victrola-style acoustic gramophones. In the succeeding years, the technology involved in speaker design underwent a significant upgrade.

In 1947, a young Naval engineer named Arthur Janszen took part in a research project for the U.S. Navy. The project focused on developing better and more accurate testing instrumentation for microphone arrays. Janszen believed that the cone speakers available then were too non-linear in phase and amplitude for their purpose, so he built an electrostatic model of his own. It had a thin, plastic diaphragm that was treated with a conductive coating, which improved phase and amplitude linearity. The electrostatic speaker was born.

By 1952, Janszen had created an electrostatic tweeter element that was ready for commercial production. It became popular amongst audio hobbyists, and was often used in conjunction with larger woofers in order to cover a wider region of the audible frequency band. It wasn’t long, however, before Janszen’s tweeter would be surpassed by another electrostatic speaker design.

Noted audio designer Peter Walker published three separate articles in the British magazine Wireless World regarding electrostatic loudspeaker designs in 1955. He posited that electrostatic speakers have an inherent ability to produce a wide bandwidth with flat frequency response, because their wide, low-mass diaphragms are uniformly driven over their surfaces by electrostatic forces. Walker backed up his articles by introducing the now famous QUAD electrostatic loudspeaker, or ESL, which raised the standard of performance for the audio industry, thanks to its remarkable design and incredible accuracy.

Over the next half-century, further advancements in the field of electrostatic loudspeaker design resulted in the formation of a competitive and rapidly evolving consumer electronics market consisting of products that provide a better and more refined listening experience. Some of the many improvements that helped usher in the age of the modern loudspeaker are the use of new cone materials, the introduction of higher-temperature adhesives, improved permanent magnet materials, more accurate measurement techniques, computer-aided design, and finite element analysis.

Main Types of Audio Speakers

Today, you will find that a wide range of loudspeaker types is available on the consumer market. Coming in just about every shape and size imaginable, today’s speakers serve a multitude of practical applications, with each type offering a unique set of advantages and disadvantages over the others. Some of the speakers that are commercially available today fall under the following major categories:

  1. Home Indoor Speakers

    These usually include bookshelf, floorstanding, computer, and in-ceiling or in-wall models. They are designed to deliver amazing sound and provide the optimal audio output for indoor use. It is worth noting, however, that some of these audio speakers do not strictly belong under this category, as they can have unique features such as wireless Bluetooth connectivity. These features make them more versatile, and ideal for outdoor environments. Indoor speakers can come as a simple stereo pair, or they can be as comprehensive as a multi-unit home audio setup.

  1. Outdoor Speakers

    True outdoor speakers typically have a robust and ruggedly durable build and construction. Sound quality usually takes a backseat to rugged design and portability, as outdoor speakers are meant to be used in even the most extreme environments. Whether it’s a picnic in the park, or a trek up the mountains, outdoor speakers can give you portable music wherever you go. Most outdoor speakers today are Bluetooth or NFC-enabled, allowing you to use your smartphone or tablet as a portable audio source. Some of them are even designed to be waterproof, letting you take it out with you even in bad weather.

  1. Car Speakers

    Whether they’re stock or aftermarket products, car speakers are designed to give consumers outstanding sound inside their vehicles. They come in varying shapes and sizes, and are built to conform with the standards and dimensions provided by each automobile manufacturer. These can either be full-range or component speakers, and are made from different woofer, tweeter, and surround materials. The main specifications to consider when buying car speakers are power handling and sensitivity.

  1. Marine Speakers

    These speakers perform the same function as car speakers, except they do it for boats and other forms of marine transportation. As such, marine speakers are made to be more robust, capable of standing up against the wind, waves, and saltwater. Sound quality isn’t always a priority with these speakers, but they do deliver sound much louder than the environment. Marine speakers can be in either a box or flush-mounted design, and are available in coaxial, triaxial, and dual cone driver configurations. An important factor to consider when buying marine speakers is its IP or Ingress Protection rating, which measures how resistant a product is against the elements.

  1. Home Theater Speaker Systems

    Combining some of the indoor speaker units mentioned earlier with a powerful subwoofer unit gives you a complete and more comprehensive home theater speaker system. When positioned correctly, these speakers produce a sound image that mimics that of a cinema or movie theater. Home theater speaker systems are available in various configurations; the most common of which are the 5.1- and 7.1-channel systems. A 5.1-channel home theater speaker system generally consists of a subwoofer, two front satellites, two rear channel satellites, and one center channel. A 7.1-channel has all those elements, with the addition to two more satellite units.

A Rapid Evolution

Loudspeakers have come a long way from the time of Johann Philipp Reis and Alexander Graham Bell, to the high-fidelity speakers that you know today; and the technology just keeps evolving. From electrostatic audio speakers, to the plasma arc design, and even to piezoelectric units, there seems to be no end to the rapidly improving audio technology that designers and engineers use today. As the demand for loudspeakers that reproduce sound as faithfully and as true to the original audio signal continues to rise, you can expect to see more advancements and innovations coming out to further enhance the way you listen.

References

https://en.wikipedia.org/wiki/Loudspeaker

http://www.edisontechcenter.org/speakers.html

http://inventors.about.com/library/inventors/blloudspeaker.htm

http://www.martinlogan.com/learn/electrostatic-loudspeaker-history.php

http://www.timetoast.com/timelines/evolution-of-speakers–2

https://www.ce.org/CorporateSite/media/CEA-Consumer-Info/Audio/Selecting-Speakers.pdf

http://www.crutchfield.com/S-Ti8KdiV17GR/learn/learningcenter/car/speakers.html

http://www.westmarine.com/WestAdvisor/Choosing-Marine-Speakers

 

 

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