On Wed, 21 Jan 2004 13:57:57 -0000, "Keith G"
wrote:


"Stewart Pinkerton" wrote in message
...
On Tue, 20 Jan 2004 16:03:11 -0000, "Keith G"
wrote:


"Stewart Pinkerton" wrote in message
...
On Mon, 19 Jan 2004 18:14:30 +0000, Julian Fowler
wrote:

On Mon, 19 Jan 2004 08:05:13 +0000 (UTC),
(Stewart Pinkerton) wrote:

On Sun, 18 Jan 2004 18:05:14 +0000, Julian Fowler
wrote:

On Sat, 17 Jan 2004 11:51:36 +0000 (UTC),
(Stewart Pinkerton) wrote:


You can get at least 200 CDs onto a 120GB hard disk if you insist
on
computer storage, and I don't know *anyone* who listens to more
than
200 different discs in an average year.

RAOTFL ...

A quick estimate suggests that I probably listen to something like
2000 different discs in an average year.

I hope you get paid for that................

Nope (and why should I?). Can't imagine what it would be like to only
listen to 200 different discs in the course of a year ...

I can't imagine how sad you have to be, to listen to half a dozen
*different* albums *every* day......................

Of course, the *audiophile* way is to listen to the *same* half dozen albums
every single day..... :-)

Made only by RR, Sheffield, Mapleshade, Linn etc, of course! :-)

And don't forget the Shaded Dogs......

Er, we're talking about high quality here - not LPs.........
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Wed, 21 Jan 2004 13:11:03 -0000
"Wally" wrote:

If I had
a low-pass filter would I still get the beat if I filtered out the 450 and
451Hz notes?

No.

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with ketchup.

Ian Molton wrote:

If I had
a low-pass filter would I still get the beat if I filtered out the
450 and 451Hz notes?

No.

So, the note doesn't exist, then?


--
Wally
www.artbywally.com

On Wed, 21 Jan 2004 18:05:55 -0000
"Wally" wrote:

If I had
a low-pass filter would I still get the beat if I filtered out the
450 and 451Hz notes?

No.

So, the note doesn't exist, then?

thats kinda like saying if I pull one leg out from under a table, does it stand up still? ;-)

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with ketchup.

Stewart Pinkerton wrote:

Please note that this kook is claiming that he listens to 2,000
*different* albums *every* year.................

Still seems perfectly reasonable to me. 30,000+ tracks on a jukebox,
playing minimum 8 hours a day + 8,000 tracks on an iPod + iTrip in
the car

I'm not saying it's impossible to achieve, I'm just wondering what
kind of nutter needs that much *new* music in his life?

I don't know because I don't listen to that much *new* music; I've had much
of it for years. I guess I get maybe 10-15 *new* albums a month

On Tue, 20 Jan 2004 18:01:55 +0000 (UTC),
(Stewart Pinkerton) wrote:

My post at 20.37 yesterday, pointing to samples of the beats that you
said shouldn't occur through one speaker.

It would be useful if you quoted these posts, since we don't all keep
archives of Usenet dross - and you did *not* obtain any such beats
with a linear system.......................
--

OK Here you are. It was a fairly prompt response to a thread in
which you were active. I can't think how you could have missed it :-)
.................................................. .................
OK, I'll make it easier for you. I've posted some demos.

http://mysite.freeserve.com/LP1/index.html

....contains two wav files.

A stereo wav containing one channel: sinewave 440Hz, the other:
sinewave 441Hz.

A mono wav containing a ,mix of the two, 6dB down, to avoid overload.

Now, on the laptop I'm using, both are mainly a demonstration of how
crap a laptop speaker is :-) At normal volume, the speaker turns it
into a square wave! But turn it low, or play on a decent system,
you'll hear the beats.

If you play the stereo file IN STEREO, the brain seems to want to turn
the beats into spatial information. "Tune in" one way, you'll hear
beats; another way, you'll hear a sound moving between the speakers.
Rather like those trick pictures that can be perceived two ways. But
mono the mix, there's no question. Even when overloading a laptop
speaker, those beats are clearly audible.

To make it easier, I've added a mono mix of the two channels. Look at
the waveform in your wave editor, listen to it. The beats are
impossible to miss!
................................................

In article , Wally wrote:
Ian Molton wrote:

If I had
a low-pass filter would I still get the beat if I filtered out the
450 and 451Hz notes?

No.

So, the note doesn't exist, then?

Indeed, it's an audible beat but it's not a separate signal in the
frequency domain. The beat is not from a mixing (i.e. non-linear)
process, but arises (AIUI) from the mathematical *identity* (if I have
derived it correctly):

sin(w1.t) + sin(w2.t) = 2 . sin((w1+w2)/2.t) . cos((w1-w2)/2.t)

So two same-amplitude sine waves at different (angular) frequencies,
w1 and w2, added (perfectly linearly) together, is the identical
equivalent of having a sine wave at the mean frequency that is 100%
amplitude modulated by a cosine wave at half the difference frequency
(t is instantaneous time in the above).

I think you will hear the amplitude variation as being at the difference
frequency itself (not half the difference). A negative amplitude is not
distinguishable audibly from a positive one and I think you will hear
the square of the amplitude modulation (i.e. at w1-w2 - twice the
modulating frequency).

So the difference tone itself does not exist - just the two original
tones. You hear the difference because of the mathematical identity
above - no process creates a separate signal.

--
John Phillips

On 22 Jan 2004 09:00:40 GMT, John Phillips
wrote:

So the difference tone itself does not exist - just the two original
tones. You hear the difference because of the mathematical identity
above - no process creates a separate signal.

It's quite loud, for something that doesn't exist :-)

As it demonstrably DOES exist, it must be the theory that is lacking -
or is inapplicable to this situation.

In article , Laurence Payne wrote:
On 22 Jan 2004 09:00:40 GMT, John Phillips
wrote:

So the difference tone itself does not exist - just the two original
tones. You hear the difference because of the mathematical identity
above - no process creates a separate signal.

It's quite loud, for something that doesn't exist :-)

As it demonstrably DOES exist, it must be the theory that is lacking -
or is inapplicable to this situation.

I do accept that the theory may be lacking or inapplicable. However in
that regard it has also to be accepted that a theory which says that
PERCEPTION of a beat at a given frequency means that the frequency EXISTS
may also be lacking or inapplicable.

--
John Phillips

On 22 Jan 2004 09:00:40 GMT, John Phillips
wrote:

In article , Wally wrote:
Ian Molton wrote:

If I had
a low-pass filter would I still get the beat if I filtered out the
450 and 451Hz notes?

No.

So, the note doesn't exist, then?

Indeed, it's an audible beat but it's not a separate signal in the
frequency domain. The beat is not from a mixing (i.e. non-linear)
process, but arises (AIUI) from the mathematical *identity* (if I have
derived it correctly):

sin(w1.t) + sin(w2.t) = 2 . sin((w1+w2)/2.t) . cos((w1-w2)/2.t)

So two same-amplitude sine waves at different (angular) frequencies,
w1 and w2, added (perfectly linearly) together, is the identical
equivalent of having a sine wave at the mean frequency that is 100%
amplitude modulated by a cosine wave at half the difference frequency
(t is instantaneous time in the above).

I think you will hear the amplitude variation as being at the difference
frequency itself (not half the difference). A negative amplitude is not
distinguishable audibly from a positive one and I think you will hear
the square of the amplitude modulation (i.e. at w1-w2 - twice the
modulating frequency).

So the difference tone itself does not exist - just the two original
tones. You hear the difference because of the mathematical identity
above - no process creates a separate signal.

Ah, superposition. Bugger...........................
--

Stewart Pinkerton | Music is Art - Audio is Engineering