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138-531: Acoustic Research, Inc. (“AR”) was founded in 1954 by audio pioneer, writer, inventor, researcher and audio-electronics teacher Edgar Villchur and his student, Henry Kloss . AR was established to produce the US$ 185 (equivalent to $ 2,070 in 2023) model AR-1, a loudspeaker design incorporating the acoustic suspension principle based on U.S. patent 2,775,309 , granted to Edgar Villchur and assigned to Acoustic Research in 1956. Edgar Villchur's technical innovation

276-398: A Stroh violin which uses a conical horn connected to a diaphragm that in turn is connected to the violin bridge. The horn was no longer needed once electrical recording was developed. The long-playing 33 1 ⁄ 3 rpm microgroove LP record , was developed at Columbia Records and introduced in 1948. The short-playing but convenient 7-inch (18 cm) 45 rpm microgroove vinyl single

414-512: A microphone was used to convert the sound into an electrical signal that was amplified and used to actuate the recording stylus. This innovation eliminated the "horn sound" resonances characteristic of the acoustical process, produced clearer and more full-bodied recordings by greatly extending the useful range of audio frequencies, and allowed previously unrecordable distant and feeble sounds to be captured. During this time, several radio-related developments in electronics converged to revolutionize

552-685: A sound track . The projector used a steady light and a photodetector to convert these variations back into an electrical signal, which was amplified and sent to loudspeakers behind the screen. Optical sound became the standard motion picture audio system throughout the world and remains so for theatrical release prints despite attempts in the 1950s to substitute magnetic soundtracks. Currently, all release prints on 35 mm movie film include an analog optical soundtrack, usually stereo with Dolby SR noise reduction. In addition, an optically recorded digital soundtrack in Dolby Digital or Sony SDDS form

690-450: A "Best Buy," and the company's sales went from $ 383,000 in 1956 to nearly $ 1,000,000 by the end of 1957. Also that year, co-founder and Vice President Henry Kloss left AR to form a new loudspeaker company, KLH . In 1958, AR once again pioneered loudspeaker technology with the introduction of the landmark model AR-3. This model used the AR-1's acoustic-suspension woofer in conjunction with

828-469: A Brahms Serenade, and the last movement of Bruckner's 8th Symphony with Von Karajan. Other early German stereophonic tapes are believed to have been destroyed in bombings. Not until Ampex introduced the first commercial two-track tape recorders in the late 1940s did stereo tape recording become commercially feasible. Despite the availability of multitrack tape, stereo did not become the standard system for commercial music recording for some years, and remained

966-513: A UK variant as the Ionophone. Electro-Voice made a model for a short time under license along with DuKane from the inventor Siegfried Klein. These early models were finicky and required regular replacement of the cell in which the plasma was generated (the DuKane unit used a precision machined quartz cell). As a result, they were expensive units in comparison to other designs. Those who have heard

1104-407: A coating of soot as the paper was passed under it. An 1860 phonautogram of " Au Clair de la Lune ", a French folk song, was played back as sound for the first time in 2008 by scanning it and using software to convert the undulating line, which graphically encoded the sound, into a corresponding digital audio file. Thomas Edison's work on two other innovations, the telegraph and the telephone, led to

1242-485: A condenser type developed there in 1916 and greatly improved in 1922, and the best amplifiers and test equipment. They had already patented an electromechanical recorder in 1918, and in the early 1920s, they decided to intensively apply their hardware and expertise to developing two state-of-the-art systems for electronically recording and reproducing sound: one that employed conventional discs and another that recorded optically on motion picture film. Their engineers pioneered

1380-402: A few crude telephone-based recording devices with no means of amplification, such as the telegraphone , it remained so until the 1920s. Between the invention of the phonograph in 1877 and the first commercial digital recordings in the early 1970s, arguably the most important milestone in the history of sound recording was the introduction of what was then called electrical recording , in which

1518-407: A high frequency line array that produces high sound pressure levels much farther away from the speaker locations than do conventional tweeters. Some loudspeaker designers use a planar magnetic tweeter, sometimes called a quasi-ribbon. Planar magnetic tweeters are generally less expensive than true ribbon tweeters, but are not precisely equivalent as a metal foil ribbon is lighter than the diaphragm in

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1656-509: A high level of complexity and sophistication. The combined impact with innovations such as the endless loop broadcast cartridge led to significant changes in the pacing and production style of radio program content and advertising. In 1881, it was noted during experiments in transmitting sound from the Paris Opera that it was possible to follow the movement of singers on the stage if earpieces connected to different microphones were held to

1794-412: A high-current amplifier. When purchased by Teledyne, AR was the world's second-largest supplier of branded loudspeakers. Although Acoustic Research continued product development, by 1989, AR had dropped to fifth place worldwide, and Teledyne sold the company to their major competitor, Jensen Electronics . In 1996, Jensen, including AR, was sold to Recoton Audio Corporation. Under both Jensen and Recoton,

1932-513: A low resonance frequency and a gentle low-end roll-off, easing crossover design. Typical of the 1960s/1970s-era was the CTS "phenolic ring" cone tweeters, exhibiting flat response from 2,000 to 15,000 Hz, low distortion and fast transient response. The CTS "phenolic ring" tweeter gets its name from the orange-colored edge suspension ring that it has which is made from phenolic. It was used in many makes and models of well-regarded vintage speakers, and

2070-585: A major consumer audio format and advances in electronic and mechanical miniaturization led to the development of the Sony Walkman , a pocket-sized cassette player introduced in 1979. The Walkman was the first personal music player and it gave a major boost to sales of prerecorded cassettes. A key advance in audio fidelity came with the Dolby A noise reduction system, invented by Ray Dolby and introduced into professional recording studios in 1966. It suppressed

2208-743: A master roll which had been created on a special piano, which punched holes in the master as a live performer played the song. Thus, the roll represented a recording of the actual performance of an individual, not just the more common method of punching the master roll through transcription of the sheet music. This technology to record a live performance onto a piano roll was not developed until 1904. Piano rolls were in continuous mass production from 1896 to 2008. A 1908 U.S. Supreme Court copyright case noted that, in 1902 alone, there were between 70,000 and 75,000 player pianos manufactured, and between 1,000,000 and 1,500,000 piano rolls produced. The first device that could record actual sounds as they passed through

2346-554: A much larger proportion of people to hear famous orchestras, operas, singers and bands, because even if a person could not afford to hear the live concert, they may be able to hear the recording. The availability of sound recording thus helped to spread musical styles to new regions, countries and continents. The cultural influence went in a number of directions. Sound recordings enabled Western music lovers to hear actual recordings of Asian, Middle Eastern and African groups and performers, increasing awareness of non-Western musical styles. At

2484-399: A piece of polarized material (i.e. some parts of the molecule are positively charged, while other parts of the molecule are negatively charged) with electrodes attached to two of its opposite faces. When an electric field is applied across the material, the polarized molecules will align themselves with the electric field, resulting in induced dipoles within the molecular or crystal structure of

2622-432: A planar magnetic tweeter and the magnetic structures are different. Usually a thin piece of PET film or plastic with a voice coil wire running numerous times vertically on the material is used. The magnet structure is less expensive than for ribbon tweeters. An electrostatic tweeter operates on the same principles as a full-range electrostatic speaker or a pair of electrostatic headphones. This type of speaker employs

2760-426: A polymer resin. Hard dome tweeters are usually made of aluminium, aluminium-magnesium alloys, or titanium. Tweeters are intended to convert an electrical signal into mechanical air movement with nothing added or subtracted, but the process is imperfect, and real-world tweeters involve tradeoffs. Among the challenges in tweeter design and manufacture are: providing adequate damping, to stop the dome's motion rapidly when

2898-434: A powerful magnetic field (typically provided by neodymium magnets) to reproduce high frequencies. The development of ribbon tweeters has more or less followed the development of ribbon microphones . The ribbon is of very lightweight material and so capable of very high acceleration and extended high frequency response. Ribbons have traditionally been incapable of high output (large magnet gaps leading to poor magnetic coupling

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3036-408: A relatively small speaker. The AR-1 set new standards for low-frequency performance and low distortion that were unsurpassed for many years. Some of the best loudspeakers available fifty years later continue to use the acoustic suspension principle for high-quality, low-distortion bass reproduction. The small size of the high-performance AR-1 permitted by the acoustic suspension design helped usher in

3174-402: A result, each performance of a song or piece would be slightly different. With the development of analog sound recording, though, a performance could be permanently fixed, in all of its elements: pitch, rhythm, timbre, ornaments and expression. This meant that many more elements of a performance would be captured and disseminated to other listeners. The development of sound recording also enabled

3312-449: A revival of vinyl in the music industry, as well as analog electronics, and analog type plug-ins for recording and mixing software. Tweeter A tweeter or treble speaker is a special type of loudspeaker (usually dome, inverse dome or horn-type) that is designed to produce high audio frequencies, typically up to 100 kHz. The name is derived from the high pitched sounds made by some birds (tweets), especially in contrast to

3450-510: A specialist market during the 1950s. EMI (UK) was the first company to release commercial stereophonic tapes. They issued their first Stereosonic tape in 1954. Others quickly followed, under the His Master's Voice (HMV) and Columbia labels. 161 Stereosonic tapes were released, mostly classical music or lyric recordings. RCA imported these tapes into the USA. Although some HMV tapes released in

3588-464: A stereo soundtrack was Walt Disney's Fantasia , released in 1940. The 1941 release of Fantasia used the Fantasound sound system. This system used a separate film for the sound, synchronized with the film carrying the picture. The sound film had four double-width optical soundtracks, three for left, center, and right audio—and a fourth as a "control" track with three recorded tones that controlled

3726-402: A thin diaphragm (generally plastic and typically PET film), with a thin conductive coating, suspended between two screens or perforated metal sheets, referred to as stators. The output of the driving amplifier is applied to the primary of a step-up transformer with a center-tapped secondary, and a very high voltage—several hundred to several thousand volts—is applied between the center tap of

3864-402: A transformer is to connect the plates of a push-pull vacuum tube amplifier directly to the stators, and the high voltage supply between the diaphragm and ground. Electrostatics have reduced even-order harmonic distortion because of their push-pull design. They also have minimal phase distortion. The design is quite old (the original patents date to the 1930s), but occupies a very small segment of

4002-469: A variety of materials including mild steel, thorn, and even sapphire. Discs had a distinctly limited playing life that varied depending on how they were manufactured. Earlier, purely acoustic methods of recording had limited sensitivity and frequency range. Mid-frequency range notes could be recorded, but very low and very high frequencies could not. Instruments such as the violin were difficult to transfer to disc. One technique to deal with this involved using

4140-429: A variety of techniques from remixing to pseudostereo . Magnetic tape transformed the recording industry. By the early 1950s, most commercial recordings were mastered on tape instead of recorded directly to disc. Tape facilitated a degree of manipulation in the recording process that was impractical with mixes and multiple generations of directly recorded discs. An early example is Les Paul 's 1951 recording of How High

4278-547: A voice coil to a dome (made of woven fabric, thin metal or other suitable material), which is attached to the magnet or the top plate via a low compliance suspension. These tweeters typically do not have a frame or basket, but a simple front plate attached to the magnet assembly. Dome tweeters are categorized by their voice coil diameter, and range from 19 mm (0.75 in), through 38 mm (1.5 in). The overwhelming majority of dome tweeters presently used in hi-fi speakers are 25 mm (1 in) in diameter. A variation

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4416-476: A wide frequency range and high audio quality are not. The development of analog sound recording in the nineteenth century and its widespread use throughout the twentieth century had a huge impact on the development of music. Before analog sound recording was invented, most music was as a live performance. Throughout the medieval , Renaissance , Baroque , Classical , and through much of the Romantic music era ,

4554-550: A worldwide standard for higher-quality recording on vinyl records. The Ernest Ansermet recording of Igor Stravinsky 's Petrushka was key in the development of full frequency range records and alerting the listening public to high fidelity in 1946. Until the mid-1960s, record companies mixed and released most popular music in monophonic sound. From mid-1960s until the early 1970s, major recordings were commonly released in both mono and stereo. Recordings originally released only in mono have been rerendered and released in stereo using

4692-474: Is amplified and connected to a loudspeaker to produce sound. Long before sound was first recorded, music was recorded—first by written music notation , then also by mechanical devices (e.g., wind-up music boxes , in which a mechanism turns a spindle, which plucks metal tines, thus reproducing a melody ). Automatic music reproduction traces back as far as the 9th century, when the Banū Mūsā brothers invented

4830-411: Is achieved by a microphone diaphragm that senses changes in atmospheric pressure caused by acoustic sound waves and records them as a mechanical representation of the sound waves on a medium such as a phonograph record (in which a stylus cuts grooves on a record). In magnetic tape recording, the sound waves vibrate the microphone diaphragm and are converted into a varying electric current , which

4968-428: Is generally shaped like an inverted dome and loads into a series of tapered channels in a central structure called a phase plug , which equalizes the path length between various areas of the diaphragm and the horn throat, preventing acoustic cancellations between different points on the diaphragm surface. The phase plug exits into a tapered tube, which forms the start of the horn itself. This slowly expanding throat within

5106-428: Is glued to a voice coil former, typically made from a different material from the dome, since it must cope with heat without tearing or significant dimensional change. Polyimide film, Nomex , and glassfibre are popular for this application. The suspension may be a continuation of the diaphragm and is glued to a mounting ring, which may fit into a groove, over locating pins, or be fastened with machine screws. The diaphragm

5244-417: Is likely to be present. An optically recorded timecode is also commonly included to synchronize CDROMs that contain a DTS soundtrack. This period also saw several other historic developments including the introduction of the first practical magnetic sound recording system, the magnetic wire recorder , which was based on the work of Danish inventor Valdemar Poulsen . Magnetic wire recorders were effective, but

5382-404: Is not required in other types), but offer the advantage that the moving mass is optimally low - if not relatively massless and so very responsive to the signal input. The early models of these tweeters were not capable of high output, nor of other than very high frequency reproduction, and so are usually used at the throat of a horn structure to manage usable output levels. One disadvantage is that

5520-455: Is quite different from more common types of tweeters (see above). Properly used, a horn improves the off-axis response of the tweeter by controlling (i.e., reducing) the directivity of the tweeter. It can also improve the efficiency of the tweeter by coupling the relatively high acoustic impedance of the driver to the lower impedance of the air. The larger the horn, the lower the frequencies at which it can work, since large horns provide coupling to

5658-446: Is the main reason). But higher power versions of ribbon tweeters are becoming common in large-scale sound reinforcement line array systems, which can serve audiences of thousands. They are attractive in these applications since nearly all ribbon tweeters inherently exhibit useful directional properties, with very wide horizontal dispersion (coverage) and very tight vertical dispersion. These drivers can easily be stacked vertically, building

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5796-423: Is the ring radiator in which the 'suspension' of the cone or dome becomes the major radiating element. These tweeters have different directivity characteristics when compared to standard dome tweeters. A piezo (or piezo-electric) tweeter contains a piezoelectric crystal coupled to a mechanical diaphragm. An audio signal is applied to the crystal, which responds by flexing in proportion to the voltage applied across

5934-422: Is then converted to a varying magnetic field by an electromagnet , which makes a representation of the sound as magnetized areas on a plastic tape with a magnetic coating on it. Analog sound reproduction is the reverse process, with a larger loudspeaker diaphragm causing changes to atmospheric pressure to form acoustic sound waves. Digital recording and reproduction converts the analog sound signal picked up by

6072-568: The Chladni patterns produced by sound in stone representations, although this theory has not been conclusively proved. In the 14th century, a mechanical bell-ringer controlled by a rotating cylinder was introduced in Flanders . Similar designs appeared in barrel organs (15th century), musical clocks (1598), barrel pianos (1805), and music boxes ( c.  1800 ). A music box is an automatic musical instrument that produces sounds by

6210-536: The compact disc (CD) in 1982 brought significant improvements in the quality and durability of recordings. The CD initiated another massive wave of change in the consumer music industry, with vinyl records effectively relegated to a small niche market by the mid-1990s. The record industry fiercely resisted the introduction of digital systems, fearing wholesale piracy on a medium able to produce perfect copies of original released recordings. The most recent and revolutionary developments have been in digital recording, with

6348-452: The graphic equalizer , which could be connected together to create a complete home sound system. These developments were rapidly taken up by major Japanese electronics companies, which soon flooded the world market with relatively affordable, high-quality transistorized audio components. By the 1980s, corporations like Sony had become world leaders in the music recording and playback industry. The advent of digital sound recording and later

6486-595: The mezzanine of Grand Central Terminal in New York City and on a street corner of Harvard Square in Cambridge, Massachusetts, where the public could stop by and listen to its products, but no sales were made there. This low-key marketing innovation boosted the company's business. AR continued to introduce new designs, and by 1966 the company had grown to hold 32.2% of the US domestic loudspeaker market, based on

6624-406: The 1920s, Phonofilm and other early motion picture sound systems employed optical recording technology, in which the audio signal was graphically recorded on photographic film. The amplitude variations comprising the signal were used to modulate a light source which was imaged onto the moving film through a narrow slit, allowing the signal to be photographed as variations in the density or width of

6762-549: The 1980s, but in the 1960s the pre-recorded 8-track tape was launched as a consumer audio format by the Lear Jet aircraft company. Aimed particularly at the automotive market, they were the first practical, affordable car hi-fi systems, and could produce sound quality superior to that of the compact cassette. The smaller size and greater durability – augmented by the ability to create home-recorded music mixtapes since 8-track recorders were rare – saw

6900-729: The AR brand continued development in the speaker industry, including the environmental controls that allowed a speaker to be placed in different room areas, the Acoustic Blanket that minimized diffraction and interference in speaker baffles, and a speaker line designed to complement home theater and the digital technologies of the 1990s. In 2003, Audiovox (now Voxx International ) acquired Recoton's US audio operations and continues developing and selling AR-brand speakers. An associated firm, AB Tech Services, provided maintenance of AR speakers until mid-2014. Web-based audiophile communities lamented

7038-516: The IHFM and High Fidelity surveys statistics for that year. This was the largest market share ever held by a loudspeaker manufacturer since statistics have been kept. The AR-3 was replaced by the AR-3a in 1969, having a new dome midrange and tweeter which were reduced in dimensions, for even better mid- and high-frequency dispersion . On September 13, 1993, an AR-3 was placed on permanent display in

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7176-719: The Information Age exhibit of National Museum of American History at The Smithsonian Institution in Washington, DC . The AR-3a was subsequently replaced by the AR-11 and AR-10pi in 1977, which shared the same improved tweeter and midrange domes. The 10pi had woofer/bass response adjustment switches to allow for a variety of room placements. The new tweeter used in the AR-11/10pi had a brighter high-frequency response, partly to compensate for reduced dispersion compared to

7314-483: The Moon , on which Paul played eight overdubbed guitar tracks. In the 1960s Brian Wilson of The Beach Boys , Frank Zappa , and The Beatles (with producer George Martin ) were among the first popular artists to explore the possibilities of multitrack recording techniques and effects on their landmark albums Pet Sounds , Freak Out! , and Sgt. Pepper's Lonely Hearts Club Band . The next important innovation

7452-526: The NAB ( National Association of Broadcasters ) standards for turntable measurements. Many AR turntable models remain in high demand. In particular, the mid-1980s models are highly modifiable to become first-rate vinyl record playback units. In 1967, Acoustic Research was bought by Teledyne , Inc., and for the next 22 years, it continued development and operations in Cambridge as Teledyne Acoustic Research . Technological breakthroughs during this period included

7590-597: The USA cost up to $ 15, two-track stereophonic tapes were more successful in America during the second half of the 1950s. The history of stereo recording changed after the late 1957 introduction of the Westrex stereo phonograph disc , which used the groove format developed earlier by Blumlein. Decca Records in England came out with FFRR (Full Frequency Range Recording) in the 1940s, which became internationally accepted as

7728-500: The additional benefit of being marginally louder than cylinders. Sales of the gramophone record overtook the cylinder ca. 1910, and by the end of World War I the disc had become the dominant commercial recording format. Edison, who was the main producer of cylinders, created the Edison Disc Record in an attempt to regain his market. The double-sided (nominally 78 rpm) shellac disc was the standard consumer music format from

7866-412: The age of stereophonic sound reproduction. Two bookshelf-sized loudspeakers were far more acceptable in a living room than the two refrigerator-sized boxes previously necessary to reproduce low-frequency bass notes. By March 1957, AR began shipping a smaller, less expensive acoustic suspension system, the US$ 87 (equivalent to $ 970 in 2023) Model AR-2. The AR-2 was selected by Consumer Reports as

8004-401: The age-old problem of bass distortion in loudspeakers caused by non-linear, mechanical suspensions in conventional loudspeakers. The existing state-of-the-art at the time of AR's invention was the bass reflex speaker, which boosted bass response for a given amount of cone travel by directing sound energy from the rear of the speaker cone through a port in the cabinet "tuned" for reinforcement of

8142-407: The air (but could not play them back—the purpose was only visual study) was the phonautograph , patented in 1857 by Parisian inventor Édouard-Léon Scott de Martinville . The earliest known recordings of the human voice are phonautograph recordings, called phonautograms , made in 1857. They consist of sheets of paper with sound-wave-modulated white lines created by a vibrating stylus that cut through

8280-492: The air at lower frequencies. There are different types of horns, including radial and constant directivity (CD). Horn tweeters may have a somewhat 'different' sonic signature than simple dome tweeters. Poorly designed horns, or improperly crossed-over horns, have predictable problems in the accuracy of their output, and the load that they present to the amplifier. Perhaps concerned about the image of poorly designed horns, some manufacturers use horn loaded tweeters, but avoid using

8418-494: The amount of data that can be stored on a single medium, such as Super Audio CD , DVD-A , Blu-ray Disc , and HD DVD became available, longer programs of higher quality fit onto a single disc. Sound files are readily downloaded from the Internet and other sources, and copied onto computers and digital audio players. Digital audio technology is now used in all areas of audio, from casual use of music files of moderate quality to

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8556-417: The background of hiss, which was the only easily audible downside of mastering on tape instead of recording directly to disc. A competing system, dbx , invented by David Blackmer, also found success in professional audio. A simpler variant of Dolby's noise reduction system, known as Dolby B, greatly improved the sound of cassette tape recordings by reducing the especially high level of hiss that resulted from

8694-555: The basis of all electronic sound systems until the commercial introduction of the first transistor -based audio devices in the mid-1950s. During World War I, engineers in the United States and Great Britain worked on ways to record and reproduce, among other things, the sound of a German U-boat for training purposes. Acoustical recording methods of the time could not reproduce the sounds accurately. The earliest results were not promising. The first electrical recording issued to

8832-454: The cassette become the dominant consumer format for portable audio devices in the 1970s and 1980s. There had been experiments with multi-channel sound for many years – usually for special musical or cultural events – but the first commercial application of the concept came in the early 1970s with the introduction of Quadraphonic sound. This spin-off development from multitrack recording used four tracks (instead of

8970-407: The cassette's miniaturized tape format. The compact cassette format also benefited from improvements to the tape itself as coatings with wider frequency responses and lower inherent noise were developed, often based on cobalt and chrome oxides as the magnetic material instead of the more usual iron oxide. The multitrack audio cartridge had been in wide use in the radio industry, from the late 1950s to

9108-447: The commercial recording, distribution, and sale of sound recordings became a growing new international industry, with the most popular titles selling millions of units by the early 1900s. A process for mass-producing duplicate wax cylinders by molding instead of engraving them was put into effect in 1901. The development of mass-production techniques enabled cylinder recordings to become a major new consumer item in industrial countries and

9246-549: The company's closure and apparent liquidation of parts stock. As of July 2014, CM Tech Support assumed responsibility for Acoustic Research parts and services. Sound recording and reproduction Sound recording and reproduction is the electrical , mechanical , electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music , or sound effects . The two main classes of sound recording technology are analog recording and digital recording . Acoustic analog recording

9384-505: The controversy came to focus on concern for the perception of moving image and sound. There are individual and cultural preferences for either method. While approaches and opinions vary, some emphasize sound as paramount, others focus on technology preferences as the deciding factor. Analog fans might embrace limitations as strengths of the medium inherent in the compositional, editing, mixing, and listening phases. Digital advocates boast flexibility in similar processes. This debate fosters

9522-456: The correct equipment, of the released music. It eventually faded out in the late 1970s, although this early venture paved the way for the eventual introduction of domestic surround sound systems in home theatre use, which gained popularity following the introduction of the DVD. The replacement of the relatively fragile vacuum tube by the smaller, rugged and efficient transistor also accelerated

9660-410: The crystal's surfaces, thus converting electrical energy into mechanical. The conversion of electrical pulses to mechanical vibrations and the conversion of returned mechanical vibrations back into electrical energy is the basis for ultrasonic testing. The active element is the heart of the transducer as it converts the electrical energy to acoustic energy, and vice versa. The active element is basically

9798-538: The cumbersome disc-to-disc editing procedures previously in some limited use, together with tape's consistently high audio quality finally convinced radio networks to routinely prerecord their entertainment programming, most of which had formerly been broadcast live. Also, for the first time, broadcasters, regulators and other interested parties were able to undertake comprehensive audio logging of each day's radio broadcasts. Innovations like multitracking and tape echo allowed radio programs and advertisements to be produced to

9936-418: The current AMT drivers in use today are similar in efficiency and frequency response to the original Oskar Heil designs of the 1970s. A horn tweeter is any of the above tweeters coupled to a flared or horn structure. Horns are used for two purposes — to control dispersion, and to couple the tweeter diaphragm to the air for higher efficiency. The tweeter in either case is usually termed a compression driver and

10074-407: The cylinder was the main consumer format from the late 1880s until around 1910. The next major technical development was the invention of the gramophone record , generally credited to Emile Berliner and patented in 1887, though others had demonstrated similar disk apparatus earlier, most notably Alexander Graham Bell in 1881. Discs were easier to manufacture, transport and store, and they had

10212-430: The development costs of new designs, pushing them out of popular price ranges. High-fidelity woofers were vulnerable to damage from extreme low-frequency signals. Those issues were addressed with the invention of the acoustic suspension woofer. The acoustic suspension woofer (sometimes known as “air suspension”) used the elasticity of air within a small, sealed enclosure of about 1.7 cu ft (48 L) to provide

10350-572: The development of the phonograph. Edison was working on a machine in 1877 that would transcribe telegraphic signals onto paper tape, which could then be transferred over the telegraph again and again. The phonograph was both in a cylinder and a disc form. On April 30, 1877, French poet, humorous writer and inventor Charles Cros submitted a sealed envelope containing a letter to the Academy of Sciences in Paris fully explaining his proposed method, called

10488-490: The development of various uncompressed and compressed digital audio file formats , processors capable and fast enough to convert the digital data to sound in real time , and inexpensive mass storage . This generated new types of portable digital audio players . The minidisc player, using ATRAC compression on small, re-writeable discs was introduced in the 1990s, but became obsolescent as solid-state non-volatile flash memory dropped in price. As technologies that increase

10626-443: The diaphragm in turn vibrates the air, thus creating air motions or audio waves, which is heard as high sounds. Modern tweeters are typically different from older tweeters, which were usually small versions of woofers . As tweeter technology has advanced, different design applications have become popular. Many soft dome tweeter diaphragms are thermoformed from polyester film, or silk or polyester fabric that has been impregnated with

10764-428: The direct signal from the front of the cone by the signal from the rear of the cone. Among the drawbacks of bass reflex design are the stringent design parameters required for accurate bass reinforcement, requiring high precision and, at the time, large cabinets. Some loss of accuracy ("smearing" or "vooming" of low frequencies) was inevitable, and the results were not entirely predictable. Extensive prototyping drove up

10902-426: The driver is continued in the horn flare. The horn flare controls the coverage pattern, or directivity, and as an acoustic transformer, adds gain. A professional horn and compression driver combination has an output sensitivity of between 105 and 112 dB/watt/meter. This is substantially more efficient (and less thermally dangerous to a small voice coil and former) than other tweeter construction. Cone tweeters have

11040-507: The earliest known mechanical musical instrument, in this case, a hydropowered (water-powered) organ that played interchangeable cylinders. According to Charles B. Fowler, this "... cylinder with raised pins on the surface remained the basic device to produce and reproduce music mechanically until the second half of the nineteenth century." Carvings in the Rosslyn Chapel from the 1560s may represent an early attempt to record

11178-444: The early 1910s to the late 1950s. In various permutations, the audio disc format became the primary medium for consumer sound recordings until the end of the 20th century. Although there was no universally accepted speed, and various companies offered discs that played at several different speeds, the major recording companies eventually settled on a de facto industry standard of nominally 78 revolutions per minute. The specified speed

11316-480: The early 1960s, AR conducted a series of over 75 live vs. recorded demonstrations throughout the United States in which the sound of a live string quartet was alternated with echo-free recorded music played through a pair of AR-3s. In this “ultimate” subjective test of audio quality, the listeners were largely unable to detect the switch from live to recorded, a strong testament to Acoustic Research's audio quality. The company also established music demonstration rooms on

11454-507: The first commercially available hemispherical (“dome”) mid-frequency midrange unit (squawker) and high-frequency tweeter . For nearly ten years after its introduction, the AR-3 was widely regarded as the most accurate loudspeaker available at any cost, and was used in many professional installations, recording studios, and concert halls. Many professional musicians used AR-3 loudspeakers as monitors because of their excellent sound reproduction. In

11592-628: The first manufacturers to fabricate dome tweeters out of a metal, copper . Nowadays other metals such as aluminium , titanium , magnesium , and beryllium , as well as various alloys thereof, are used, being both light and stiff but having low damping; their resonant modes occur above 20 kHz. More exotic materials, such as synthetic diamond , are also being used for their extreme stiffness. Polyethylene terephthalate film and woven silk suffer less ringing, but are not nearly as stiff, which can limit their very high frequency output. In general, smaller dome tweeters provide wider dispersion of sound at

11730-404: The fixed magnetic field of a permanent magnet around which the cylindrical voice coil is suspended, forcing the voice coil and the diaphragm attached to it to move. This mechanical movement resembles the waveform of the electronic signal supplied from the amplifier's output to the voice coil. Since the coil is attached to a diaphragm, the vibratory motion of the voice coil transmits to the diaphragm;

11868-402: The high recording speeds required, they used enormous reels about one meter in diameter, and the thin tape frequently broke, sending jagged lengths of razor steel flying around the studio. Magnetic tape recording uses an amplified electrical audio signal to generate analogous variations of the magnetic field produced by a tape head , which impresses corresponding variations of magnetization on

12006-484: The higher power levels typically encountered. High frequency drivers in PA horns are often referred to as " compression drivers " from the mode of acoustic coupling between the driver diaphragm and the horn throat. Various materials are used in the construction of compression driver diaphragms including titanium, aluminium, phenolic impregnated fabric, polyimide and PET film , each having its own characteristics. The diaphragm

12144-517: The highest frequencies. However, smaller dome tweeters have less radiating area, which limits their output at the lower end of their range; and they have smaller voice coils, which limit their overall power output. Ferrofluid is a suspension of very small (typically 10 nm) iron oxide magnetic particles in a very low volatility liquid, typically a synthetic oil. A wide range of viscosity and magnetic density variants allow designers to add damping, cooling, or both. Ferrofluid also aids in centering

12282-506: The late ‘70s, such as the Celef PE1 in which they were utilised as a super tweeter in combination with a conventional dome tweeter. They are often used in toys, buzzers, alarms, bass guitar speaker cabinets, cheap computer or stereo speakers and PA horns. A ribbon tweeter uses a very thin diaphragm (often of aluminum, or perhaps metalized plastic film) that supports a planar coil frequently made by deposition of aluminium vapor, suspended in

12420-399: The low woofs made by many dogs , after which low-frequency drivers are named ( woofers ). Nearly all tweeters are electrodynamic drivers using a voice coil suspended within a fixed magnetic field. These designs operate by applying current from the output of an amplifier circuit to a coil of wire called a voice coil . The voice coil produces a varying magnetic field, which works against

12558-540: The main way that songs and instrumental pieces were recorded was through music notation . While notation indicates the pitches of the melody and their rhythm many aspects of the performance are undocumented. Indeed, in the Medieval era, Gregorian chant did not indicate the rhythm of the chant. In the Baroque era, instrumental pieces often lack a tempo indication and usually none of the ornaments were written down. As

12696-691: The market because of high costs, low efficiency, large size for full range designs, and fragility. The Air Motion Transformer tweeter works by pushing air out perpendicularly from the pleated diaphragm. Its diaphragm is the folded pleats of film (typically PET film) around aluminium struts held in a strong magnetic field. In past decades, ESS of California produced a series of hybrid loudspeakers using such tweeters, along with conventional woofers, referring to them as Heil transducers after their inventor, Oskar Heil . They are capable of considerable output levels and are rather more sturdy than electrostatics or ribbons, but have similar low-mass moving elements. Most of

12834-547: The material. This alignment of molecules will cause the material to change dimensions. This phenomenon is known as electrostriction . In addition, a permanently polarized material such as quartz (SiO 2 ) or barium titanate (BaTiO 3 ) will produce an electric field when the material changes dimensions as a result of an imposed mechanical force. This phenomenon is known as the piezoelectric effect . Piezo tweeters rarely get used in high-end audio because of their low fidelity, although they did feature in some high-end designs of

12972-475: The microphone to a digital form by the process of sampling . This lets the audio data be stored and transmitted by a wider variety of media. Digital recording stores audio as a series of binary numbers (zeros and ones) representing samples of the amplitude of the audio signal at equal time intervals, at a sample rate high enough to convey all sounds capable of being heard . A digital audio signal must be reconverted to analog form during playback before it

13110-411: The mid-1980s. Cone tweeters are now rarely used in modern hi-fi usage and are routinely seen in low cost applications such as factory car speakers, compact stereo systems, and boom boxes. Some boutique speaker manufacturers recently have returned to high-end cone tweeters, especially recreations of CTS phenolic ring models, to create a vintage-sounding product. A dome tweeter is constructed by attaching

13248-651: The most demanding professional applications. New applications such as internet radio and podcasting have appeared. Technological developments in recording, editing, and consuming have transformed the record , movie and television industries in recent decades. Audio editing became practicable with the invention of magnetic tape recording , but technologies like MIDI , sound synthesis and digital audio workstations allow greater control and efficiency for composers and artists. Digital audio techniques and mass storage have reduced recording costs such that high-quality recordings can be produced in small studios. Today,

13386-402: The moving tape. In playback mode, the signal path is reversed, the tape head acting as a miniature electric generator as the varyingly magnetized tape passes over it. The original solid steel ribbon was replaced by a much more practical coated paper tape, but acetate soon replaced paper as the standard tape base. Acetate has fairly low tensile strength and if very thin it will snap easily, so it

13524-599: The next few years, the lesser record companies licensed or developed other electrical recording systems. By 1929 only the budget label Harmony was still issuing new recordings made by the old acoustical process. Comparison of some surviving Western Electric test recordings with early commercial releases indicates that the record companies artificially reduced the frequency range of recordings so they would not overwhelm non-electronic playback equipment, which reproduced very low frequencies as an unpleasant rattle and rapidly wore out discs with strongly recorded high frequencies. In

13662-488: The next two years, Blumlein developed stereo microphones and a stereo disc-cutting head, and recorded a number of short films with stereo soundtracks. In the 1930s, experiments with magnetic tape enabled the development of the first practical commercial sound systems that could record and reproduce high-fidelity stereophonic sound . The experiments with stereo during the 1930s and 1940s were hampered by problems with synchronization. A major breakthrough in practical stereo sound

13800-405: The only issued electrical recording. Several record companies and independent inventors, notably Orlando Marsh , experimented with equipment and techniques for electrical recording in the early 1920s. Marsh's electrically recorded Autograph Records were already being sold to the public in 1924, a year before the first such offerings from the major record companies, but their overall sound quality

13938-416: The paleophone. Though no trace of a working paleophone was ever found, Cros is remembered by some historians as an early inventor of a sound recording and reproduction machine. The first practical sound recording and reproduction device was the mechanical phonograph cylinder , invented by Thomas Edison in 1877 and patented in 1878. The invention soon spread across the globe and over the next two decades

14076-467: The plasma arc can produce ozone and NOx , poison gases, in small quantities as a by-product. Because of this, German-made Magnat "magnasphere" speakers were banned from import to the United States in the 1980s. Any modern design uses catalysts to reduce the gas output to negligible quantities. In the past, the dominant manufacturer in the US was DuKane near St Louis, who made the Ionovac; also sold in

14214-665: The playback volume of the three audio channels. Because of the complex equipment this system required, Disney exhibited the movie as a roadshow, and only in the United States. Regular releases of the movie used standard mono optical 35 mm stock until 1956, when Disney released the film with a stereo soundtrack that used the Cinemascope four-track magnetic sound system. German audio engineers working on magnetic tape developed stereo recording by 1941. Of 250 stereophonic recordings made during WW2, only three survive: Beethoven's 5th Piano Concerto with Walter Gieseking and Arthur Rother,

14352-808: The process of making a recording is separated into tracking, mixing and mastering . Multitrack recording makes it possible to capture signals from several microphones, or from different takes to tape, disc or mass storage allowing previously unavailable flexibility in the mixing and mastering stages. There are many different digital audio recording and processing programs running under several computer operating systems for all purposes, ranging from casual users and serious amateurs working on small projects to professional sound engineers who are recording albums, film scores and doing sound design for video games . Digital dictation software for recording and transcribing speech has different requirements; intelligibility and flexible playback facilities are priorities, while

14490-549: The public, with little fanfare, was of November 11, 1920, funeral service for The Unknown Warrior in Westminster Abbey , London. The recording engineers used microphones of the type used in contemporary telephones. Four were discreetly set up in the abbey and wired to recording equipment in a vehicle outside. Although electronic amplification was used, the audio was weak and unclear, as only possible in those circumstances. For several years, this little-noted disc remained

14628-590: The recording industry. Tape made possible the first sound recordings totally created by electronic means, opening the way for the bold sonic experiments of the Musique Concrète school and avant-garde composers like Karlheinz Stockhausen , which in turn led to the innovative pop music recordings of artists such as the Beatles and the Beach Boys . The ease and accuracy of tape editing, as compared to

14766-540: The recording process. These included improved microphones and auxiliary devices such as electronic filters, all dependent on electronic amplification to be of practical use in recording. In 1906, Lee De Forest invented the Audion triode vacuum tube, an electronic valve that could amplify weak electrical signals. By 1915, it was in use in long-distance telephone circuits that made conversations between New York and San Francisco practical. Refined versions of this tube were

14904-417: The restoring force for the woofer cone. The entrapped air of the sealed-loudspeaker enclosure, unlike the mechanical springs of conventional speakers, provided an almost linear spring for the woofer's diaphragm, enabling it to move back and forth large distances (“excursion”) in a linear fashion, a requirement for the reproduction of deep bass tones. The disadvantage of this arrangement is low efficiency. Since

15042-428: The restoring force is large with a large woofer in a small cabinet, the cone must be massive to keep the resonant frequency in the required low bass region. The AR-1s were about 10 percent as efficient as other (physically much larger) existing speakers with equivalent bass response, but since higher power amplifiers were becoming available about the same time, this was a reasonable trade-off to get good bass response from

15180-646: The rights to the Blattnerphone, and newly developed Marconi-Stille recorders were installed in the BBC's Maida Vale Studios in March 1935. The tape used in Blattnerphones and Marconi-Stille recorders was the same material used to make razor blades, and not surprisingly the fearsome Marconi-Stille recorders were considered so dangerous that technicians had to operate them from another room for safety. Because of

15318-537: The room's corners, a common practice in the 1950s, 1960s and early 1970s. During the 1970s and 1980s, the widespread introduction of higher quality audiophile discs and the advent of the CD caused the cone tweeter to fall out of popularity because cone tweeters seldom extend past 15 kHz. Audiophiles felt that cone tweeters lacked the "airiness" of dome tweeters or other types. Nevertheless, many high-end cone tweeters remained in limited production by Audax, JBL and SEAS until

15456-466: The sale of consumer high-fidelity sound systems from the 1960s onward. In the 1950s, most record players were monophonic and had relatively low sound quality. Few consumers could afford high-quality stereophonic sound systems. In the 1960s, American manufacturers introduced a new generation of modular hi-fi components — separate turntables, pre-amplifiers, amplifiers, both combined as integrated amplifiers, tape recorders, and other ancillary equipment like

15594-595: The same basic design and form as a woofer with optimizations to operate at higher frequencies. The optimizations usually are: Cone tweeters were popular in older stereo hi-fi speakers designed and manufactured in the 1960s and 1970s as an alternative to the dome tweeter (which was developed in the late 1950s). Cone tweeters today are often relatively cheap, but many of those in the past were of high quality, such as those made by Audax/Polydax, Bozak, CTS, JBL, Tonegen and SEAS. These vintage cone tweeters exhibited very flat frequency response, low distortion, fast transient response,

15732-505: The same tape many times, sounds could be duplicated from tape to tape with only minor loss of quality, and recordings could now be very precisely edited by physically cutting the tape and rejoining it. Within a few years of the introduction of the first commercial tape recorder—the Ampex 200 model, launched in 1948—American musician-inventor Les Paul had invented the first multitrack tape recorder , ushering in another technical revolution in

15870-514: The same time, sound recordings enabled music lovers outside the West to hear the most famous North American and European groups and singers. As digital recording developed, so did a controversy commonly known as the analog versus digital controversy. Audio professionals, audiophiles, consumers, musicians alike contributed to the debate based on their interaction with the media and the preferences for analog or digital processes. Scholarly discourse on

16008-429: The signal ends; ensuring suspension linearity, allowing high output at the low end of its frequency range; ensuring freedom from contact with the magnet assembly, keeping the dome centered as it moves; and providing adequate power handling without adding excessive mass. Tweeters contribute to a well-balanced and rich audio experience by focusing on the higher sound frequencies. Tweeters can also work in collaboration with

16146-566: The sound quality was poor, so between the wars, they were primarily used for voice recording and marketed as business dictating machines. In 1924, a German engineer, Kurt Stille, improved the Telegraphone with an electronic amplifier. The following year, Ludwig Blattner began work that eventually produced the Blattnerphone, which used steel tape instead of wire. The BBC started using Blattnerphones in 1930 to record radio programs. In 1933, radio pioneer Guglielmo Marconi 's company purchased

16284-479: The system and both made their earliest published electrical recordings in February 1925, but neither actually released them until several months later. To avoid making their existing catalogs instantly obsolete, the two long-time archrivals agreed privately not to publicize the new process until November 1925, by which time enough electrically recorded repertory would be available to meet the anticipated demand. During

16422-435: The term. Their euphemisms include "elliptical aperture" "Semi-horn" and "Directivity controlled". These are, nonetheless, a form of horn loading. Because ionized gas is electrically charged and so can be manipulated by a variable electrical field, it is possible to use a small sphere of plasma as a tweeter. Such tweeters are called a plasma tweeter or ion tweeter. They can be more complex than other tweeters (plasma generation

16560-838: The theory that the smallest baffle possible is optimal for tweeters. Most tweeters are designed to reproduce frequencies up to the formally defined upper limit of the human hearing range (typically listed as 20 kHz); some operate at frequencies up to approximately in between 5 kHz to 20 kHz. Tweeters with a greater upper range have been designed for psychoacoustic testing, for extended-range digital audio such as Super Audio CD intended for audiophiles , for biologists performing research on animal response to sounds, and for ambient sound systems in zoos. Ribbon tweeters have been made that can reproduce 80 kHz and even 100 kHz. All dome materials have advantages and disadvantages. Three properties designers look for in domes are low mass, high stiffness and good damping. Celestion were

16698-460: The transformer and the diaphragm. Electrostatics of this type necessarily include a high voltage power supply to provide the high voltage used. The stators are connected to the remaining terminals of the transformer. When an audio signal is applied to the primary of the transformer, the stators are electrically driven 180 degrees out of phase, alternately attracting and repelling the diaphragm. An uncommon way of driving an electrostatic speaker without

16836-478: The tweeter of the AR3a. AR produced a low-cost ($ 68 in 1963) belt-drive turntable , a type of phonograph , using a cast aluminum 3.3 lb (1.5 kg) turntable platter suspended with a T-bar sub-chassis that greatly reduced acoustic feedback. A 24-pole hysteresis-synchronous, permanent magnet Hurst AC motor propelled the platter via a precision ground rubber belt to produce very low wow and flutter , exceeding

16974-495: The two ears. This discovery was commercialized in 1890 with the Théâtrophone system, which operated for over forty years until 1932. In 1931, Alan Blumlein , a British electronics engineer working for EMI , designed a way to make the sound of an actor in a film follow his movement across the screen. In December 1931, he submitted a patent application including the idea, and in 1933 this became UK patent number 394,325 . Over

17112-615: The two used in stereo) and four speakers to create a 360-degree audio field around the listener. Following the release of the first consumer 4-channel hi-fi systems, a number of popular albums were released in one of the competing four-channel formats; among the best known are Mike Oldfield 's Tubular Bells and Pink Floyd 's The Dark Side of the Moon . Quadraphonic sound was not a commercial success, partly because of competing and somewhat incompatible four-channel sound systems (e.g., CBS , JVC , Dynaco and others all had systems) and generally poor quality, even when played as intended on

17250-450: The use of a set of pins placed on a revolving cylinder or disc so as to pluck the tuned teeth (or lamellae ) of a steel comb. The fairground organ , developed in 1892, used a system of accordion-folded punched cardboard books. The player piano , first demonstrated in 1876, used a punched paper scroll that could store a long piece of music. The most sophisticated of the piano rolls were "hand-played," meaning that they were duplicates from

17388-566: The use of mechanical analogs of electrical circuits and developed a superior "rubber line" recorder for cutting the groove into the wax master in the disc recording system. By 1924, such dramatic progress had been made that Western Electric arranged a demonstration for the two leading record companies, the Victor Talking Machine Company and the Columbia Phonograph Company . Both soon licensed

17526-909: The voice coil in the magnetic gap, reducing distortion. The fluid is typically injected into the magnetic gap and is held in place by the strong magnetic field. If a tweeter has been subjected to elevated power levels, some thickening of the ferrofluid occurs, as a portion of the carrier liquid evaporates. In extreme cases, this can degrade the sound quality and output level of a tweeter, and the fluid must be removed and new fluid installed. Tweeters designed for sound reinforcement and musical instrument applications are broadly similar to high fidelity tweeters, though they're usually not referred to as tweeters, but as "high frequency drivers". Key design requirement differences are: mountings built for repeated shipping and handling, drivers often mounted to horn structures to provide for higher sound levels and greater control of sound dispersion, and more robust voice coils to withstand

17664-409: The woofers that are responsible for generating the low frequencies or bass. Some tweeters sit outside the main enclosure in their own semi-independent unit. Examples include " super tweeters " and the novel "egg tweeter" by Ohm . The latter plugs in and swivels to adjust the soundfield depending on listener position and user preference. The separation from the baffle is considered to be optimal under

17802-549: Was 78.26 rpm in America and 77.92 rpm throughout the rest of the world. The difference in speeds was due to the difference in the cycle frequencies of the AC electricity that powered the stroboscopes used to calibrate recording lathes and turntables. The nominal speed of the disc format gave rise to its common nickname, the "seventy-eight" (though not until other speeds had become available). Discs were made of shellac or similar brittle plastic-like materials, played with needles made from

17940-411: Was a mid-priced unit. Cone tweeters have a narrower dispersion characteristic that is the same as a cone woofer's. Many designers therefore believed this made them a good match to cone midranges and woofers, allowing for superb stereo imaging. However, the "sweet spot" created by the narrow dispersion of cone tweeters is small. Speakers with cone tweeters offered the best stereo imaging when positioned in

18078-414: Was acceptable. The compact 45 format required very little material. Vinyl offered improved performance, both in stamping and in playback. Vinyl records were, over-optimistically, advertised as "unbreakable". They were not, but they were much less fragile than shellac, which had itself once been touted as "unbreakable" compared to wax cylinders. Sound recording began as a purely mechanical process. Except for

18216-412: Was based on objective testing and research, most of which was made publicly available as documents, specifications, and measurements—all of which were then new in the loudspeaker industry. Acoustic Research, as an employer, claimed equal opportunity and offered liberal employee benefits , insurance , and profit sharing to its employees. The acoustic suspension woofer provided an elegant solution to

18354-459: Was further improved just after World War II by American audio engineer John T. Mullin with backing from Bing Crosby Enterprises. Mullin's pioneering recorders were modifications of captured German recorders. In the late 1940s, the Ampex company produced the first tape recorders commercially available in the US. Magnetic tape brought about sweeping changes in both radio and the recording industry. Sound could be recorded, erased and re-recorded on

18492-530: Was in turn eventually superseded by polyester. This technology, the basis for almost all commercial recording from the 1950s to the 1980s, was developed in the 1930s by German audio engineers who also rediscovered the principle of AC biasing (first used in the 1920s for wire recorders ), which dramatically improved the frequency response of tape recordings. The K1 Magnetophon was the first practical tape recorder, developed by AEG in Germany in 1935. The technology

18630-411: Was introduced by RCA Victor in 1949. In the US and most developed countries, the two new vinyl formats completely replaced 78 rpm shellac discs by the end of the 1950s, but in some corners of the world, the 78 lingered on far into the 1960s. Vinyl was much more expensive than shellac, one of the several factors that made its use for 78 rpm records very unusual, but with a long-playing disc the added cost

18768-448: Was made by Bell Laboratories , who in 1937 demonstrated a practical system of two-channel stereo, using dual optical sound tracks on film. Major movie studios quickly developed three-track and four-track sound systems, and the first stereo sound recording for a commercial film was made by Judy Garland for the MGM movie Listen, Darling in 1938. The first commercially released movie with

18906-479: Was small cartridge-based tape systems, of which the compact cassette , commercialized by the Philips electronics company in 1964, is the best known. Initially a low-fidelity format for spoken-word voice recording and inadequate for music reproduction, after a series of improvements it entirely replaced the competing consumer tape formats: the larger 8-track tape (used primarily in cars). The compact cassette became

19044-410: Was too low to demonstrate any obvious advantage over traditional acoustical methods. Marsh's microphone technique was idiosyncratic and his work had little if any impact on the systems being developed by others. Telephone industry giant Western Electric had research laboratories with material and human resources that no record company or independent inventor could match. They had the best microphone,

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