The Outer Shell
 

On Sun, 28 Nov 2004 01:38:59 +0000, Spiderant wrote:

snip

Unfortunately, because my in-laws live below us, I'm relegated to
listening to most of my music through headphones, which means that
although the sweet spot never varies, but the in-the-head stereophonic
image is not optimal.

snip

Have a look for "binaural" stuff. This is recorded using a dummy head and
can be almost frightningly convincing when listened to via headphones.
http://www.binaural.com/binfaq.html

For some more interesting headphone stuff look he
http://www.headwize.com/projects/
The "Signal Processors" heading has several designs for "enhancing"
headphone listening on normal stereo recordings. These remove the "hole in
the middle" effect that you sometimes get.

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info
Web: http://projectedsound.tk

The Outer Shell
 

In article , Kalman
Rubinson
wrote:
Thanks for making a clearer statement than I did. The issue is,
however, that there is more information to be gleaned from the signal
than the OP is seeing when he looks at the 'scope.

Agreed. :-) The problem here is encapsulated in your "seeing" as it seems
that the OP is not yet able to recognise the significance of what he would
see,

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

The Outer Shell
 

Spiderant wrote:

"Stewart Pinkerton" wrote in message
...

On Fri, 26 Nov 2004 03:32:36 GMT, "Spiderant"
wrote:
You are forgetting one critical point in a modern recording - it's in
stereo. The very best, in accuracy terms, are made using minimalist
microphone techniques in real concert halls, and they can replicate
the ambience of the hall extremely well.


I have thought about this. I also understand (I think) how stereo
microphones and subsequently speakers would help create the illusion of
three dimensional sound (sort of like those Viewmaster 3D Viewers we all
played with as kids, but for ears).

The sonic equivalent of the Viewmaster would be Binaural Stereo
or Dummy Head recording, used many years ago by the BBC for some
radio plays. There are a few records made with this technique
though the only ones I have are by Edgar Froese from the seventies.

I'm still not grasping why the original signal(s)
would contain more than the peripheral information of frequency extremes at
any given point in time.


The only "information" that your eardrum passes is its instantaneous
displacement just as a microphone does.


Given a good stereo recording, as described above, the soundfield
reaching your head will closely mimic that which would reach your ears
in the original concert hall at the microphone position, and sure
enough, you can 'focus' on individual performers by slight movement of
your head in the same way.

That's the problem with binaural stereo. It sounds as though your head
is stationary. It would be amusing to fit motion sensors to the phones
and actuators to the dummy head so that the microphones move as your
head does. This of course would only work for a single live session.

Unfortunately, because my in-laws live below us, I'm relegated to listening
to most of my music through headphones, which means that although the sweet
spot never varies, but the in-the-head stereophonic image is not optimal.

Some people deliberately add crosstalk/delay when listening to a normal
recording on phones to improve the image. I've not tried it myself.


--
Eiron.

The Outer Shell
 

In article , Nick Gorham
wrote:
Spiderant wrote:
[snip]


Hi,

I think Jim can do this much better, but the little I know. To actually
state how much informatoin is being sent, you need to know a couple of
things, the range of frequences being transmitted, and the signal to
noise ratio, given that you can actually calculate the amount of
information, Lookup Shannon in the text books. However, i don't you are
using the word information is such a formal sense.

FWIW the above looks fine to me. :-)

The simple and quick answer, is yes, at a particular point in time there
is only a single voltage being produced by the source, but thats just
one part of the story, at a point in time just before that, the voltage
was at a different level, and at a point in the future it will be at yet
another voltage. So you could regard the signal as a sequence of
instantanious voltage levels, and the information is encoded in this
ever changing level.

May be useful to add the following:

Think of the outer parts of the ears as being pressure detectors. These
pick up the way in which the sound pressure varies with time, and then
convey this pressure-time pattern (or 'waveform') into the inner ear.

The inner ear then examines and analyses the vibration waveform and can
symultaneously recognise many different details.

This isn't simply a matter of whether the pressure level is 'positive' or
'negative' at any one time. The precise shape of the waveform matters, and
tiny details or changes in the shape of the pressure-time patterns can
produce audible effects.

The microphones pick up the pressure-time patterns, and produce
voltage-time patterns which should have the same 'shape' and convey the
same 'details'. The amount of information carried depends upon how tiny a
detail may be conveyed and by how brief (in time) a detail can be conveyed.

The ability to convey tiny details is limited by noise. The ability to
convey brief details is limited by the range of frequencies the microphone,
etc, can respond to.

Hence all the details of the shapes matter, and the amount of info is
limited by the noise level (compared with the signal level we wish to
convey) and the bandwidth (range of frequencies) conveyed.

Of course, it is much more complicated than the above - that's why we still
all end up arging about it. :-)

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

The Outer Shell
 

In article , Glenn Booth
wrote:

[snip]


If you decide you really want to know about all this stuff and you have
free time, look up TA225 (The technology of music) on the open
University web site. It's a bargain, but it will be better next year
(when it's finished!).

[Side note to Jim Lesurf - if you looking for some interesting work, get
in touch with the OU - the TA225 course started this year, and they
could use some help - far too many mistakes, some of which I am still
disputing with them, even after the exam!]

You make me interested in the site, so I may well investigate at some
point.

Alas, I can't really do very much 'academic' work these days for the same
reason as had to take early retirement. :-/ Hence 'large' projects are
likely to be beyond me these days!

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

The Outer Shell
 

On Sun, 28 Nov 2004 01:50:23 GMT, "Spiderant"
wrote:

I really appreciate your pointing me in the right direction in this and
previous posts. I've come to the realization that my understanding of basic
audio principles is very limited. I picked up some audio books from the
library, which I'll peruse before asking more questions. BTW Your previous
post about analog waveforms will be the focus of my research.

Don't worry about it. Your willingness to learn places you very high
in the rankings of 'serious audiophiles'. It's always good to remember
that you should aleways keep an open mind, but be careful that your
brain does not fall out in the process! :-)

Out of curiousity Jim, why do you sign your emails with the term "Slainte"?
I live on the West Coast of Canada and I've never heard the word. What does
it mean?

Try some Scots Canadians! It's a Gaelic word meaning 'health', the
full expression is Slainte Mhor. Pronounced 'Slaandjivaa' It literally
means 'big health', but is taken as the ubiquitous 'cheers', and is
the appropriate toast for whisky drinkers.

As an aside, in Jacobean households during the early 18th century, the
'loyal' toast would often be said while passing the charged glass over
the top of the water jug, the toast being 'good health over the
water', a reference to the Pretenders to the Throne of Scotland, the
Stuarts who were in France at the time.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

The Outer Shell
 

In article T_9qd.366396$nl.259331@pd7tw3no, Spiderant
wrote:
[snip]
I remember reading about how Eliahu Inbal was a strong proponent of dual
microphones. I have a CD of him conducting Mahler's 7th Symphony where
he is using only two microphones. I'm actually listening to this as
I'm writing. If you have any recommendations of good recordings using
dual mikes, I'm sure that more newsgroup readers than I would
appreciate hearing about them.

Some people do advocate various 'pure and simple' microphone techniques
like the above. There are two snags, though.

One is that such methods can be quite demanding on the skill of the
engineer, and the conductor - as well as on the acoustics of the recording
location. Thus it may give lovely results in some cases, but sound hopeless
in others.

FWIW The Bartok "Concerto for Orchestra" recording on Mercury I mentioned
in a recent posting is a Robert Fine/Wilma Cozart recording using just 3
microphones. Some of their 'Mercury' recordings (and lesser known ones that
used to be on the 'Pye' label) do employ 'simple' methods to get quite good
results. My copy of the Baryok is a CD-A Mercury 432 017-2, but I think it
may have been re-issued since then.

The other snag I mention below...

Unfortunately, because my in-laws live below us, I'm relegated to
listening to most of my music through headphones, which means that
although the sweet spot never varies, but the in-the-head stereophonic
image is not optimal.

This is the second snag. Most recordings tend to be produced assuming you
are listening via loudspeakers. Hence you may find that some recordings
sound excellent via speakers, but less satisfactory via headphones. :-/

[snip]

Totally agree. The trick is to find the good system while on a tight
budget.

Indeed. :-)

However if you are using headphones you can side-step one of the main
sources of bother/expense by not having to worry so much about the
loudspeakers and room acoustics.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

The Outer Shell
 

In article z9aqd.366477$nl.121146@pd7tw3no, Spiderant
wrote:
[snip]


Out of curiousity Jim, why do you sign your emails with the term
"Slainte"? I live on the West Coast of Canada and I've never heard the
word. What does it mean?

It is Gaelic. It is part of a 'toast' which (approximately) says "Good
Health! Great Health!"

The English equivalent is "Cheers!" but since emigrating to Scotland I
decided that Slainte is a better and more appropriate word. :-)

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

A big thanks to all the posters
 

"Spiderant" wrote in message
news:8oaqd.357363$Pl.271729@pd7tw1no...
The many excellent responses to my original question have inspired me to
do some research on audio properties. In the interim, I'm still enjoying
my music, although I'm going through a horrible dilemma now as to whether
I prefer vinyl or CDs (as I talked about in the Neil Young thread). On my
way to the library this afternoon to pick up some books on audio, I
stopped at our local Salvation Army store and did something I haven't done
in a long, long time. I started browsing through their used LPs. I ended
up picking up a pristine copy of Toscanini conducting Beethoven's first
and ninth symphonies, as well as a LP of Richter playing some Beethoven
piano sonatas. At one twentieth the price of a CD for each LP, I figured I
would try it. Of course my wife crossed her arms and gave me a dirty (not
in the nice way) look when I came back home. Half a year ago I gave away
a significant portion of my LP collection to clear up some space for her
plants and she's not about to let me do some selective pruning. So, I
guess that means I'll be listening to music tonight. Oh well, things
could be worse.

Thanks again to all the respondents in my favorite audio newsgroup.

Keep it lit,

Roland Goetz.


Try to work it out so when your wife is picking up the groceries you are
delving through the charity shops. As you've already found there are some
good vinyl recordings still to be had at reasonable prices, though some
charity shops are getting wise to this - one shop referred to the 'Penguin
price guide for Record & CD Collectors' before charging!! I bear in mind
its for charity and its nearly Christmas...up to a point ;-)

Mike

The Outer Shell
 

"Jim Lesurf" wrote
This isn't simply a matter of whether the pressure level is 'positive' or
'negative' at any one time. The precise shape of the waveform matters, and
tiny details or changes in the shape of the pressure-time patterns can
produce audible effects.

Well yeah but any waveform is just a sum of a load of sinusoidal waves
anyway, by Fourier.

Depends how you look at it.

Anyway, this whole thing is a bit more complex than pressure-versus-time
anyway, because sound is NOT perceived by inputting an electrical
representation of the pressure signal into some wetware "black box" which
does processing on the signal to work out what the sound is.

Rather, in the cochlea, there's a tube, with a bit running along the middle
of it, and a load of tiny hairs, and IIRC, different points along that
structure detect different frequencies, and each hair (or maybe proximate
small group of hairs) sends a signal down a nerve to a part of the brain.
So it's far from simple, to imagine what kind of processing may be going on,
with all those many, many inputs to the brain.

A computer would typically recognise sound (e.g. speech recognition) by
analysing ONE input signal. This is much simpler than what's going on in
our ears/brains, though ISTM that it's possible that our system loses some
phase information.


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.fleetie.demon.co.uk