maxdimario wrote on Mon, 07 March 2005 11:30 |
a system with an extended high freq. response is more likely to be stable at lower frequencies, but limiting bandwidth to 20 Khz in a non destructive way (if this is possible) will not change our ear's perception of the sound...
some mics don't go any higher than 20-22 Khz.
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a system with an extended high freq. response is more likely to be stable at lower frequencies, but limiting bandwidth to 20 Khz in a non destructive way (if this is possible) will not change our ear's perception of the sound.Stay on topic please. Some people in audio advocate higher bandwidth on the grounds that we hear- “extra high” frequency transients. I say it is wrong to have separate criteria for transient bandwidth and steady state. The same bandwidth that defines the music, defines all of it, transient or not.
The advocates of the high frequency transients story theorize that one can hear a difference when introducing high frequency energy at frequencies above steady state listening tests. I have been explaining that transient high frequency energy (not steady state) comes with (is coupled with) an audible energy, unless special conditions are met (narrow transients occurring very far apart). Therefore, listening to a difference does not prove that one hears high frequency energy.
This thread is about dispelling the BS about our ability to hear transients at higher frequencies than the rest of the music (such steady state tone hearing tests). It is NOT about what bandwidth to use when designing for good audio performance.
some mics don't go any higher than 20-22 Khz.Most mics, and speakers do not go above 20KHz, yet we had a suggestion to do a listening test with a 40KHz burst. When Joe suggested to take a 44.1KHz signal, up sample to 96KHz and add a 40KHz burst, he should have also said VERY STRONGLY to be sure that everyone (including himself) use speakers or headphone capable of at least 40KHz. The irony here is that anyone following the suggested test and is hearing sonic difference on standard speakers, would be actually proving my point which is that the energy is within the speaker bandwidth, in most cases not over 20KHz.
This is an example of the kind of half-baked BS we are dealing with. To begin with, the proposed 40KHz burst test is missing the issue about high frequency transients also having low frequency content (due to the transient “envelope”). And again, given that whatever one hears, cannot be attributed to the energy above the speaker bandwidth, it is not “extra” high frequency energy. In other words, those that followed the instructions (how to do a 40KHz burst) carefully, and heard a difference with normal speakers or headphone, have in fact proved my point experimentally. And the few (anyone?) that happened to be equipped with a 40KHz speaker are in no position to say that it is high frequency they hear.
Feel free to start a thread about bandwidth and circuits or whatever. I know I am being extra stubborn here about not changing the subject. Here is why:
I am trying to dispel a myth, and there are many people that do not want to hear what I say. One of the common methods to put a damper on my comment is to CHANGE THE SUBJECT. Once it is changed, other people get off track and the message gets lost.
In a previous post you said “the ears know best”. Indeed the ears can tell you IF something was heard, The brain can tell you IF what you heard is liked, if it sounds like the original (assuming you heard the original). The HOW and WHY questions must be answered by a scope or test gear.
The ear can differentiate a 1KHz square from sine wave, but does not know that there are exactly 20 possible harmonics in the square wave (to 20KHz), that only the odd harmonics exist and so on. The ear cannot tell you much technical information. The ear may not be the tool to tell you if a subtle sonic difference is due to some low level base band activity or some 40KHz.
It is true that the brain can be well trained to recognize differences in pitch, timbre and much more. We can all tell a piano note at 200Hz from a 1KH flute
However, the statement “the ear knows best” does not belong in a technical discussion.
For example, it takes more than an ear to know about hearing frequencies beyond human hearing, which is the subject of this thread
Regards
Dan Lavry
www.lavryengineering.com