转一篇国外关于盲听的研究

cfming

交易区新帖推荐

http://www.avguide.com/forums/blind-listening-tests-are-flawed-editorial

大体能看懂

catkingyes

看不懂，压力大

小白

这个文章很有意思啊。作者Robert Harley可是大腕级的人物。

他开篇说到的那个盲听也很有意思——16比特、44.1K取样的CD音频，和24比特、96K取样的高码率音频，以及SACD，根本是无法区分、音质完全一样的？60个expert listeners（有经验的听众，应该是指发烧友），在一次盲听测试中无法区分出CD规格音频与24/96的高码率音频。这次盲听还写成报告，发表在2007年9月的AES学报上。

小白

接下来Robert Harley先生还提到了一个结论更为荒谬的著名盲听试验——在一次1987年的盲听试验中，结论似乎表明，双单声道的Mark Levinson放大器、一台OTL胆机、一台220美金价格的先锋放大器，声音是一样、无法区分的！那次盲听试验的过程和结论发表在1987年1月的Stereo Review杂志上。

小白

下面这个例子就十分有意思了。我会大致翻译一下，原文是：

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?

大致说就是，瑞典电台设想用一种低码率的压缩格式来代替FM广播。为了确认这一压缩格式的声音是否足够好，他们做了广泛的盲听测试，牵涉到60个有经验的试验者（expert listeners）进行了总共20000次的“听”。最后盲听测试的结果似乎表明这种压缩格式不会对音质造成可闻的劣化。最后瑞典电台基于盲听测试的结果，决定采用这种压缩格式来播放。做出这个决定后，瑞典电台把一盘经过这种压缩格式处理的音乐磁带寄给一位专家——已故的Bart Locanthi。这位先生是数码音频领域内的权威人物。然而这位Locanthi没有采取盲听的方式，只是用传统的试听方式，10分钟内就发觉这种压缩格式其实是有损音质的，并且指出了它的具体失真。在他指出问题之后，瑞典电台的试验人员们马上也注意到了这个失真！
为什么一个有经验的听者，Bart Locanthi先生，能在10分钟内找出问题，而60个有经验的听者，按照严格的盲听原则，在2年的盲听时间中，进行了2万次的聆听，却无法找出这个问题？

cfming

白版的英文水平好厉害

comnetedu

小白专业是学外语的

cfming

啊，这样啊，怪不得呢

wujiapeng

1. Bart Locanthi发现有损只是一个巧合。
2. 不够合理的盲听会产生误导作用。

yao_qin

原帖由 wujiapeng 于 2011-3-27 14:03 发表
1. Bart Locanthi发现有损只是一个巧合。
2. 不够合理的盲听会产生误导作用。

不够合理的盲听听不出去区别不是因听法不合理，而是因为区别不够大。

嫫失嫫忘

我觉得似乎都觉得盲听更“公平”是因为怕传统的试听方式带来某种心理暗示。
但究竟这些潜在的暗示是不是在人为添加某种并不存在的区别或差异，还是仅仅提供了适当的参考呢？。。不晓得~
可能人与人也不一样吧

catkingyes

白版很好地证明了区别不大的话就算有损也无所谓了 ，反正听不出:D

qoiuiop

这，是一个心理学的问题？

cfming

仔细看了下，发现应该是大体看不懂