On 12/2/2010 8:55 AM, [email protected] wrote: > The guy told me the THD was 0.1 % to which I > replied "but the human ear cannot distinguish a THD much below 1 %." And > he replied, "of course, you can't hear it, that's why we have the > oscilloscope." The price for the system was in excess of $10,000.
As an audio professional (and a Fellow of the AES), I can tell you that THD is a poor indicator of equipment performance or audibility. It's not that the numbers don't matter, but rather that simple-minded descriptors like THD are not useful. The human ear DOES hear harmonic distortion at levels as low as 0.02%, but it depends on the ORDER of the harmonic (that is, which harmonic). The second harmonic can be somewhat pleasing, and some studio EFX boxes add second harmonic. The control that adjusts the level of the second harmonic is called "warmth." In general, orders of harmonics that relate to western musical scales (octaves) are least objectionable, and high orders are most objectionable. Third order harmonic distortion is no pleasant. It is those higher orders that are audible at low levels. Also, any non-linear process produces both harmonics and intermod. Some intermod products are also quite audible at fairly low levels, while others that are common to western musical scales are less audible. 73, Jim Brown K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
