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Old 28th April 2013, 04:44 AM   #1
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I was looking for another paper and came across this ancient BBC Research paper http://ia600601.us.archive.org/28/it...10/1957_10.pdf
In it D. E. L. Shorter found that skilled listeners could not hear the effect of 12 kHz low pass.

This would imply that there is no need for 20mm vs 25mm dome tweeters.
I have also noticed that super tweeters have dropped out of fashion recently
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Old 28th April 2013, 05:09 AM   #2
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Very interesting article - I haven't read it !

But the date - Uh ! Oh! 1957 !
at that time, they ( space dept. R&D ) wanted to go to the moon, and they managed to do it ten years later.

Meanwhile, sound storage and reproduction technique had evolved.
AR introduced the dome tweeter ( ? )
Amplifiers had become more linear
With the introduction of the CD you were guaranteed to have 20-20000 flat
Nowadays the increase of quantization in digital technology had lifted the 20 KHz limit to 40 KHz, but still we cannot hear frequencies above 20 KHz.
Speakers have much more better 'impulse response' behavior than 20 years ago .
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Old 28th April 2013, 11:43 AM   #3
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The BBC were perfectly capable of recording and playback to 20 kHz back then. It is interesting that few listeners could detect cutting to 10 kHz. There were records being cut with plenty of 20 kHz content like John Colrane "Giants Steps".
I presume this was some of the research that lead to VHF radios 15 kHz bandwidth.
The listeners probably had better hearing than we do, as they were not exposed to over-amplified rock concerts and in ear headphones
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Old 28th April 2013, 03:31 PM   #4
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Well, still very interesting
And I still haven't read the article!
The end of your phrase makes me thinking....you know, those things like muzak or at the extremes, rave parties . Also my father, who started me incounsciously to high fidelity, he always asks me : why are you doing this/ that ? When the purpose is only to listen to the music !?!
So it's a matter of culture, but personal one . Everyone will elaborate a piece of music in his/her own way. That's why I don't trust that kind of statistic research : I would like to know each person interviewed, but very insightfully !
It's not only a matter of phisiological structure ( ear/brain) but historical.
Internet should be the instrument to share our feelings related to audio, it's a big gathering where everyone can make a report, by writing..it remains there!
Probably those people in the late '50s haven't had a proper hi-fi set up.
Most probably, it happened that the instant before and after they changed their attention, forgot some particular...who can tell ? You have to mould yourself to the sound of music...and music travels with the sound.
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Old 29th April 2013, 06:59 PM   #5
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Quote:
Originally Posted by davidsrsb View Post
The BBC were perfectly capable of recording and playback to 20 kHz back then. It is interesting that few listeners could detect cutting to 10 kHz. There were records being cut with plenty of 20 kHz content like John Colrane "Giants Steps".
I presume this was some of the research that lead to VHF radios 15 kHz bandwidth.
The listeners probably had better hearing than we do, as they were not exposed to over-amplified rock concerts and in ear headphones
In this study, between the program material and the speaker there was a 10 to 15 dB attenuation of 15kHz compared to 12 kHz.
On top of that attenuation, HF (high frequency) masking (white) noise was introduced post playback so the difference in tape noise was not noticed with different filters, further masking what little HF material existed in the program material.

The speaker's response on axis was down 5 dB at 15kHz from 12 kHz, and off axis where 2/3rd's of the listeners stood, presumably another 5 dB down, or more as most HF transducers "beam" at HF.
Tape playback resulted in a 2.5 dB or 5 dB loss depending on re-recording.
Some of the microphones used for the recordings also had additional HF loss.

A 10 dB difference at 1kHz sounds about half as loud, at 15 kHz, we need approximately an additional 5 dB more SPL to sound as loud as 12.5kHz, so the level presented to the listeners at 15 kHz would only sound 1/4 as loud for the on-axis listeners (only 1/3 of the listeners).

The upper limit of my hearing presently is only a bit more than 15kHz in my right ear, a bit less than 15 kHz in my left.
Even with my limited upper frequency range, with any program material that has a fair amount of HF content I can clearly hear the difference when the 16 kHz 1/3 octave filter is reduced by 10 dB on the Alesis DEQ 830 used in my home stereo.

The Alesis DEQ filters are very precise, pulling the 16kHz band down 10-12 dB only results in a few dB loss at 12.5 kHz.

At any rate, loosing the 1/3 octave band between 12.5kHz and 16kHz is apparent about as much as loosing the 1/3 octave band between 31.5 and 40 Hz.

Unfortunately, at the rate my HF hearing is going as I age, in another decade or two, I won't be able to notice any difference above 12 kHz.
My girlfriend (born in the year of the study cited) still can hear 20 kHz quite well, while memories of hearing 18kHz for me are from decades ago..

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