Science Fair Project Encyclopedia
- High Fidelity is also the title of a book by Nick Hornby and a film directed by Stephen Frears, based upon Hornby's book.
High fidelity (or HiFi or hi-fi) is the reproduction of sound and image that is very faithful to the original. Hi-fi aims to achieve minimal or unnoticeable amounts of noise and distortion. The term "hi-fi" can be applied to any reasonable quality home music system. Hi-fi enthusiasts are often known as audiophiles or videophiles.
The 1920s saw the introduction of electronic amplification, microphones, and the application of quantitative engineering principles to the reproduction of sound. Much of the pioneering work was done at Bell Laboratories and commercialized by Western Electric. Acoustically recorded disc records, with capriciously peaky frequency response, were replaced with electrically recorded ones. The Victor Orthophonic phonograph, although purely acoustic, was created by engineers who applied waveguide technology to the design of the interior folded horn to produce a smooth frequency response which complemented and equalled that of the electrically-recorded Victor Orthophonic records.
Meanwhile, the rise of radio was popularizing the use of sound reproduction by means of tube amplifiers and loudspeakers, so you had the curious anomaly of a period of time during which radio receivers commonly used loudspeakers and electronic amplifiers to produce sound, while phonographs were still commonly purely mechanical and acoustic.
The advent of the microgroove vinyl record, with low surface noise and quantitatively specified equalization curves, created the conditions for a major improvement of home audio quality, through the application of electronics to phonographs. In the 1950s, the term "high fidelity" began to be used by audio manufacturers as a marketing term to describe records and equipment which was intended to provide faithful sound reproduction. To synthesize a definition, the term "high fidelity," if it had a definite meaning, probably meant that the amplifier incorporated the proper LP equalization curve, and that equipment characteristics such as frequency response and distortion had at least been measured.
The ordinary consumer simply interpreted "hi-fi" as a magical marketing term for fancy and expensive equipment and bought hi-fi records (RCA "New Orthophonic," London "ffrr") and, if they could afford them, "hi-fi" phonographs. Audiophiles paid attention to technical characteristics, bought individual components (separate preamplifiers, amplifiers), and frequently assembled their own speaker systems.
In the 1950s "hi-fi" became a generic term, to some extent displacing "phonograph" and "record player." Rather than playing a record "on the phonograph," people would play it "on the hi-fi."
In the late 1950s and early 1960s the development of the Westrex single-groove stereophonic record led to the next wave of home audio improvement, and in common parlance "stereo" displaced "hi-fi." Records were now played on "a stereo." In the world of the audiophile, however, "high fidelity" continued and continues to refer to the goal of highly accurate sound reproduction, and to the technological resources available for approaching that goal.
A very popular type of system for reproducing music from the 1970s onwards is the integrated music centre, a natural successor to the older stereogram or radiogram . Purists will generally avoid referring to these systems as high fidelity, though some are capable of very good quality reproduction nevertheless.
Ascertaining high-fidelity: the double-blind tests
Attempted improvements in hardware (equipment like microphones, loudspeakers, etc.) should really be tested by "double-blind (D-B)" listening comparisons, before they are offered for sale. If this is not done, it is unfortunately too easy for "power of suggestion" to convince people that the new thing is audibly better.
Many new developments in this field are measurably better, for example the ability to reproduce frequencies above 30 kHz, but nobody can hear the difference, so they are not audibly better. It is sometimes easy to convince yourself that a new thing sounds different, but a double-blind test prevents anyone from identifying which equipment is new versus old. The D-B test involves hiding both the old and new equipment from view, and taking notes on which one the listener thinks sounds better, with all notes written in code. That could be a single-blind test, but if even the person operating the switch does not know which is new or old, then it is double-blind. After the test is completed, the notes are decoded.
This kind of testing has been required in the approval of new medicines since about 1960. However, the D-B audio listening test was first described by Dan Shanefield, in November of 1974, in the newsletter of the Boston Audio Society. This was later reported to the general public in High Fidelity Magazine, March 1980. The D-B listening comparison is now a standard procedure with most audio professionals. (It should be mentioned that a few manufacturers of very expensive audio equipment still dispute the need for this test.) A commonly used improvement of this test is the ABX listening comparison. This involves comparing two known audio sources (A and B) with either one of those when it has been randomly selected (X). The test, and its associated equipment, was developed by the Southeastern Michigan Woofer and Tweeter Marching Society ("SMWTMS"), a semi-pro, semi-amateur organization in Detroit, which is very active in the double-blind testing of new audio components.
Integrated (also Midi or Lifestyle) systems contain one or more sources (e.g.CD, Radio, or Cassette), together with preamplifier and power amplifier in one box. (The name has no connection with MIDI technology in electronic instruments). Such products are generally disparaged by audiophiles, although some high end manufacturers produce integrated systems.
The traditional hi-fi enthusiast will build a system from separates, often with each item from a different manufacturer specialising in a particular component. This allows the opportunity to choose components which complement each other's perceived sonic characteristics, and allows a piece-by-piece upgrade at a later date.
- Audio system measurements
- Digital Audio Broadcast (DAB)
- Home cinema
- Further discussions of the double-blind test and its history and importance are on the bottom half of this long page.
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