On 10/03/2015 2:29 AM, Java Jive wrote:
On Mon, 09 Mar 2015 12:58:54 +1100, Trevor Wilson
wrote:

On 9/03/2015 2:15 AM, Java Jive wrote:
As I said earlier, these days manufacturers take even less care with
vinyl than they do with other media sources.

CD technology could and should have given us a flat FR from near DC up
to 25kHz, easily covering the range of human hearing.

**Bull****. With a sampling rate of 44.1kHz, Nyquist tells us that the
theoretical maximum of CDs is 22.05kz.

As it was actually implemented it was something of a compromise,
sacrificing FR to give greater playing time, but the space available
on the prototype technology "COULD AND SHOULD" (note what I actually
wrote) have been allocated differently to give us a shorter playback
time at a higher sampling rate that would have covered the range of
human hearing.

Even going up
to 22kHz it still covers quite comfortably the range of older
listeners such as myself.

**It actually covers pretty much everyone over the age of 10.

I and several others tested the range of our hearing in the Physics
Lab at college when I was about 17 or 18, and I wasn't the only one in
the group who could hear above 23KHz at that age.

**AT WHAT LEVEL?

The human ear does not have a 'brickwall filter' at 20kHz. No one ever
suggested it did. I recall visiting a warehouse owned by the company I
worked for when I was around 25 years old. I was assaulted by the most
appalling 'feeling' and I had to immediately leave. Curious, I decided
to work out what was going on. Turns out I was reacting to the
ultrasonic burglar alarm system. A microphone, preamp, oscilloscope and
frequency counter showed me that the space in the warehouse was
constantly flooded with a high intensity acoustic signal of
approximately 26kHz. OTOH, using conventional hearing tests, my hearing
extended to around 19kHz at the time.

MORAL: With sufficient intensity, human hearing can extend way past
20kHz. That intensity is NEVER achieved with any commercial recordings.




--
Trevor Wilson
www.rageaudio.com.au

---
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Java Jive wrote:


I and several others tested the range of our hearing in the Physics
Lab at college when I was about 17 or 18, and I wasn't the only one in
the group who could hear above 23KHz at that age.


** Fraid that has been thoroughly proven to have nothing to do with music reproduction.

No matter how many naïve audiophools think it does.



..... Phil

Dave Plowman ( Raving Nutcase) wrote:


The reasons for the original CD spec are all based around the limits of
the PCM recorders of the day - basically a semi-pro video recorder
(U-matic).


** The CD spec was *tweaked* to be compatible with those recorders - hence sampling at 44.1kHz instead of some other very similar number. It is NOT a quality limitation.


As we know from later, CD itself is capable of a longer playing time.

** The original CD was smaller than the final 12cm dia version, chosen to increase the playing time to well over 1 hour.

44.1kHz and 16 bit gives audibly perfect reproduction plus a comfortable margin beyond. 100dB s/n and 0.005% THD are well beyond what is necessary.


.... Phil

Trevor Wilson wrote:


**AT WHAT LEVEL?


** Certainly over 100dB SPL.

Easily achieved with headphones or a tweeter held close to one's ear while being fed from a sine wave generator and amplifier.



.... Phil

In article ,
Phil Allison wrote:
The reasons for the original CD spec are all based around the limits of
the PCM recorders of the day - basically a semi-pro video recorder
(U-matic).


** The CD spec was *tweaked* to be compatible with those recorders -
hence sampling at 44.1kHz instead of some other very similar number. It
is NOT a quality limitation.

Never said it was. I was absolutely blown away when I attended the first
UK demonstration of CD - as were all of my colleagues.

As we know from later, CD itself is capable of a longer playing time.

** The original CD was smaller than the final 12cm dia version, chosen
to increase the playing time to well over 1 hour.

The limit of an NTSC U matic tape was also 74 minutes of programme
material. Allowing for line-up. PAL was 90 minutes.

44.1kHz and 16 bit gives audibly perfect reproduction plus a comfortable
margin beyond. 100dB s/n and 0.005% THD are well beyond what is
necessary.

Absolutely. I've never said different.

--
*I used up all my sick days so I called in dead

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (Rabid Nutcase) wrote:


The reasons for the original CD spec are all based around the limits of
the PCM recorders of the day - basically a semi-pro video recorder
(U-matic).


** The CD spec was *tweaked* to be compatible with those recorders -
hence sampling at 44.1kHz instead of some other very similar number. It
is NOT a quality limitation.

Never said it was.

** Yes you did.



As we know from later, CD itself is capable of a longer playing time.

** The original CD was smaller than the final 12cm dia version, chosen
to increase the playing time to well over 1 hour.

The limit of an NTSC U matic tape was also 74 minutes of programme
material. Allowing for line-up. PAL was 90 minutes.

** Yawnnnnn....


44.1kHz and 16 bit gives audibly perfect reproduction plus a comfortable
margin beyond. 100dB s/n and 0.005% THD are well beyond what is
necessary.

Absolutely. I've never said different.


** But you snidely implied differently.



..... Phil

In article , Java Jive
wrote:

After some searching I've just found some AC recordings of tracks from
an album that I now have on CD, it's Barbara Dickson's seminal folk
album "From The Beggar's Banquet", 1970. The AC recordings were
originally made from a library copy of the LP, while the CD is a
re-issue of 5 or 6 years ago that I feel most fortunate to have
obtained. The difference between the two is utterly unmistakable.

Alas the LP and CD come into that if you're trying to assess AC.
Particularly if you've not heard the LP for a long time and become
habituated to the AC.

FWIW I also routinely find that an LP sounds different to a CD of the
'same' material. The problem being that this may be down to the two
versions being 'mastered' sic quite differently. Can tell you more about
the people cutting the LP or 'improving' sic again what they put on LP
than it does about the frequency response capabilities of either system.

All comes down to how much care and skill were applied when producing the
LP or CD, and to the replay systems.

A couple of days ago I made a digital copy of a 1960 LP of Schubert
symphonies conducted by Beecham. Early EMI stereo LP. The sound is lovely.
And with far fewer ticks and clicks than from later EMI LPs. On-center and
flat disc, too! Just a tragedy that as time passed EMI ceased to take care
when making either LPs *or* CDs and the results sounded worse as a result.
Bean counters were more interested in "Who cares about manufacturing
quality if we can sell them and they don't come back. How quickly and
cheaply can me make them?"

From the LPs I have I'd say that during the early 'stereo' years EMI did
make some great LPs with real care. But by the mid 1970s they simply turned
out 'product' and it was a matter of luck what you got. They relied on you
wanting to hear those artists and bits of music. The hifi mag pages
routinely carried letters bewailing the poor pressings, etc. Yet it
remained clear that a well-made LP could sound very good. Sadly, they got
harder to find!

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

On 09/03/2015 20:49, Trevor Wilson wrote:


MORAL: With sufficient intensity, human hearing can extend way past
20kHz.


I wouldn't exactly call the sensation of a high level 20 kHz tone
'hearing' more like 'detection'. My normal hearing barely extends to
9-10 kHz these days but I was aware of an odd clicking sensation (best
way I can describe it) in an a relatives garden. Turned out to be a cat
repellent gadget. Sensation vanished when it was switched off.

I've also been aware of a vaguely uncomfortable feeling standing close
to a shop window that had some sort of 'anti-teen' sound device
installed. Couldn't hear anything at all...just an awareness of
something unpleasant. And I'm no teen.

In article ,
Phil Allison wrote:
The reasons for the original CD spec are all based around the
limits of the PCM recorders of the day - basically a semi-pro
video recorder (U-matic).


** The CD spec was *tweaked* to be compatible with those recorders -
hence sampling at 44.1kHz instead of some other very similar number.
It is NOT a quality limitation.

Never said it was.

** Yes you did.

Should have realised you'd put your own spin on 'limits'.

Should also have known there is absolutely no point in trying to have a
discussion with you.

--
*I never drink anything stronger than gin before breakfast *

Dave Plowman London SW
To e-mail, change noise into sound.

In article , Sumatriptan
wrote:
On 09/03/2015 20:49, Trevor Wilson wrote:


MORAL: With sufficient intensity, human hearing can extend way past
20kHz.


I wouldn't exactly call the sensation of a high level 20 kHz tone
'hearing' more like 'detection'. My normal hearing barely extends to
9-10 kHz these days but I was aware of an odd clicking sensation (best
way I can describe it) in an a relatives garden. Turned out to be a cat
repellent gadget. Sensation vanished when it was switched off.

I've also been aware of a vaguely uncomfortable feeling standing close
to a shop window that had some sort of 'anti-teen' sound device
installed. Couldn't hear anything at all...just an awareness of
something unpleasant. And I'm no teen.


FWIW Oohashi and others published research papers some years ago which
reported doing things like brain scans whilst people listened to sound
with/without and 'ultrasonic' portion.

Played by itself, people couldn't hear the 'ultrasound'. But their
brainscans were different with/without it when the main music was played.

So it seems possible that high frequency tones which are - in isolation -
'inaudible' may affect our perception when they accompany clearly audible
lower frequency sounds.

This isn't particularly surprising if true since human hearing physiology
is known to be highly nonlinear.

What it means for listening to music is harder to say. But it does make it
plausible that there *might* be some advantage in having bandwidths above
20kHz even when you can't hear isolated tones at that frequency, at least
in some cases.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html