Trumpai, radau įdomios medžaigos (pateikiu tekstą žemiau, anglų kalba), apie aklus testus iš grynai Pro srities - Švedijos radijo perėjimas prie kitų standartų/kodekų. Esminis dalykas - 20.000 aklų testų ir 60 PRO ekspertų nesugebėjo PASTEBĖTI techninio kodeko artefakto 1.5kHz dažnyje , kurį per 10 min pastebėjo VIENINTELIS audiofilas, PIRMOJE perklausoje. KODĖL? Istorija: Most such tests, including this new CD vs. high-res comparison, are performed not by disinterested experimenters on a quest for the truth but by partisan hacks on a mission to discredit audiophiles. But blind listening tests lead to the wrong conclusions even when the experimenters’ motives are pure. A good example is the listening tests conducted by Swedish Radio (analogous to the BBC) to decide whether one of the low-bit-rate codecs under consideration by the European Broadcast Union was good enough to replace FM broadcasting in Europe. Swedish Radio developed an elaborate listening methodology called “double-blind, triple-stimulus, hidden-reference.” A “subject” (listener) would hear three “objects” (musical presentations); presentation A was always the unprocessed signal, with the listener required to identify if presentation B or C had been processed through the codec. The test involved 60 “expert” listeners spanning 20,000 evaluations over a period of two years. Swedish Radio announced in 1991 that it had narrowed the field to two codecs, and that “both codecs have now reached a level of performance where they fulfill the EBU requirements for a distribution codec.” In other words, Swedish Radio said the codec was good enough to replace analog FM broadcasts in Europe. This decision was based on data gathered during the 20,000 “double-blind, triple-stimulus, hidden-reference” listening trials. (The listening-test methodology and statistical analysis are documented in detail in “Subjective Assessments on Low Bit-Rate Audio Codecs,” by C. Grewin and T. Rydén, published in the proceedings of the 10th International Audio Engineering Society Conference, “Images of Audio.”) After announcing its decision, Swedish Radio sent a tape of music processed by the selected codec to the late Bart Locanthi, an acknowledged expert in digital audio and chairman of an ad hoc committee formed to independently evaluate low-bit rate codecs. Using the same non-blind observational-listening techniques that audiophiles routinely use to evaluate sound quality, Locanthi instantly identified an artifact of the codec. After Locanthi informed Swedish Radio of the artifact (an idle tone at 1.5kHz), listeners at Swedish Radio also instantly heard the distortion. (Locanthi’s account of the episode is documented in an audio recording played at workshop on low-bit-rate codecs at the 91st AES convention.) How is it possible that a single listener, using non-blind observational listening techniques, was able to discover—in less than ten minutes—a distortion that escaped the scrutiny of 60 expert listeners, 20,000 trials conducted over a two-year period, and elaborate “double-blind, triple-stimulus, hidden-reference” methodology, and sophisticated statistical analysis? The answer is that blind listening tests fundamentally distort the listening process and are worthless in determining the audibility of a certain phenomenon. Šaltinis: http://www.avguide.com/forums/blind-listening-tests-are-flawed-editorial?page=1