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2 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 is 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.
3 Modularity
The equipments can be compact or modular. Modular have diferent pieces for the ensemble and are more flexible.
4 Modern Equipment
Nowadays HiFi equipment includes CD players, DAB and internet radio and modern connections ( fiber optic TOSlink and multiple ones) and ports ( USB, WiFi).
If they include DVD, Liquid crystal display television and other components, it's another system called home cinema.
5 See also
6 External links
Audio
