【理性與熱情】家訪 hojuiyang111

[kevintran]

From http://www.diyaudio.com/forums/multi...ml#post1506291
by Lynn Olson
"There's a little story I heard a long time ago. Los Angeles, home of Altec and JBL, was deeply resistant to time-based measurement methodologies. It was swept-sinewave or nothing for these guys.

Just to stir things up, Richard Heyser sprang a little surprise at a Los Angeles AES meeting. It was a little black box that had very low distortion, measured completely flat using Altec and JBL's swept-sinewave methodologies, yet was so grossly distorted that speech was unlistenable. Much head-scratching ensued - and Dick already had a well-established reputation as one of those Caltech wise guys.

At the end of the talk, he revealed the secret of the black box: it was a very high-order allpass filter, that was randomly switched in and out of the signal path. It completely garbled the time domain in the fashion of an especially bad shortwave signal.
［恕刪］2.

謝謝您提供這個出處。我個人覺得這個故事的重點不是測量有沒有用，而是測量的方法和解讀的方式正不正確。

就像魔術師在舞台上表演魔術一樣：台下的觀眾看的一愣一愣的，但是要是說穿了.......