Why do intelligent people deny audio differences?

perception based upon sensation is not fact, it is opinion.

Mrtennis, does anybody buy a speaker if they don't think it sounds good? We certainly survive based on our use of our senses and our ears can sense the full range of sound, not merely some limited aspects.

Greeni,
You make a really interesting point-- which is no doubt true.
The 'measurable'(I'm paraphrasing my own thoughts as to your meaning here, how's that for a stretch?)is always preferable in terms of testing, to the obvious.
You said, and I agree:
"Our culture, the educational system reinforced this tendency. We tend to equate intelligence with a logical mind and sensibility, and dismiss our intuitive and creative faculty."
So, (I'm agreeing again, just being provocative), one must ask some questions regarding logical versus creativity AND intuition and their relative merit.

"Who taught Willie Shakespeare to write?"
"Who taught DaVinci about physics, in a world before the concept of physics was even thought about by the masses?"
(Think, helicopters, gross anatomy and other such things that he speculated on), AND by the way, his I.Q. while impossible to calculate has been guestimated to be in the neighborhood of 220. Since, 100 is the 'norm' that means that his core capactity is 2.2 Times that...I think that's probably really, really a low guess.
"Who taught Pasteur?"
"Who taught Mario Puzzo?"

So, while your 'creative' comments and the lack of appreciation are clearly on the mark, MOST of what has shaped this world has been 'created' by someone special.

When I first met Jim Thiel, and was new to audio...I asked him, "Where did you study."
When I met John Iverson, (of Electron Kinetics fame) I asked him the same.
They both just shook their heads, no doubt thinking..."Oh, I went to UK (Lexington) or IU, (Bloomington) and studied Loudspeaker building 101 thru 404 and 'Amplifier Creation'
101 thru 404.
Those of us who can create and intuit, do this without any logical jumping off point it seems--and those who need emperical data, sometimes sit back and evaluate those who have.
Somehow that seems really wrong to me.

Good listening,
Larry

Lrsky, you and Greeni have certainly entered into a discussion I have never seen in any audio postings. I think you are neglecting observation, such as Newton realizing everything fell toward the earth and wondered about it, Rontgen the x-ray or De Forest the vacuum tube building on Edison. Certainly, education does impart the ability to build on what other's observed as did De Forest.

Then come explanations and a theory as to why one variable affects another, such as the dielectric constant affecting the transfer speed in a cable.

I guess I think such people who watch and listen and wonder why one thing causes changes in another move us ahead in understanding nature and what is going on. They know how little we know.

I have always argued that why cables sound different, why component breakin, etc. is not explained by much of what we know and imparted in our educations. I have known or know several who are innovative in audio. Often when I ask them where they came up with an idea, I get strange answers, such as it just came to me, I just hear what this circuit would sound like, or I accidentally did this and was shocked by the sound.

Curiosity is probably our strongest capability. Fifty years from now, people will wonder how we could have listened to MP3.

This is an intriguing topic for me, not least because of a recent incidence. A couple of weeks ago I was selling over head-fi my Grado RS2i headphone, a much sought after item, to a gentleman in Sweden. On my way to the post office I got a vague hunch that I should cancel the transaction, but because the Swedish gentleman has already paid then I did not heed my intuition and went ahead and shipped the parcel to Sweden. Not long thereafter I received an email from the buyer that he received the parcel but was forced to pay heavy custom duties because I have specified the value of the phone on the accompanying shipping documents. I wasn’t conscious of the issues because I shipped like these from my country to the US many times without problem. To pacify the Swedish gentleman I made a refund to him, so that the net price was such that I would never have sold the phones at such low price. I told the Swedish gentleman what happened, and that the refund was my tuition fees for not listening to that fleeting inner voice. He wrote me back “you should always listen to your intuition”.

Now this incidence seemingly has no bearing to the OP’s question of why do intelligent people deny audio differences, but I do see a correlation. I guess sooner or later one would come across people who insist only upon the measurable, logical, the calculated way that everything that cannot comes to terms within which framework are literally banished, repressed, push away, much like the OP’s brother holding a Masters Degree in Education would not acknowledge perceivable audio differences, when everyone else could hear it. The reason this person would not acknowledge perceivable audio differences is akin to the mistake I made when my conscious reasoning mind is not willing to acknowledge the vague feeling that something is wrong, because logically I could not sensibly discern a reason thereof. In the same way the OP's brother could not hear audio differences with cables because the frequency spectrum should scientifically be all the same.

I don’t know who taught DaVinci about physics, but I asked what makes his Mona Lisa such work of art. One could, of course, says that she has a mysterious smile or that there is something elusive about her, etc., but truth be told our reasoning minds are not able to explain that very thing that makes this painting a masterpiece. That which speak to the heart do so in a language not comprehend by the logical mind. The conscious mind plan, solves problem, etc., the unconscious mind transcend.

IMHO there exists vast difference between intelligent and wise, one of which being the latter acknowledge there is only so much that the mind could comprehend, and requires a healthy dose of humbleness.