[Arny Krueger[_4_]]

"Soundhaspriority" wrote in message
...


"Mxsmanic" wrote in message
...
Soundhaspriority writes:

Mxsmanic's worry that speakers on a salt flat won't sound good is
intuition that results from experience we've all had.

I've seen it done pretty confincingly. Please see my former posts for the
*how*.

Actually I don't know if they'd sound good or not, I was just wondering.

All this stuff about speakers sounds extremely complicated. I think
headphones
are a better choice. Headphones give you more control over what is going
into
each ear, and that's what it is ultimately all about, right?

Headphones can provide superior sonic accuracy in terms of reproduction of
the recording.

That one is tough, too. The ear-brain localization system is deprived of
cues provided by the external ear and skull. Sometimes the signal is
manipulated to restore the cues. Or, we get used to the headphone
experience and do without.

The above ignores the fact that the cues in question should, in many
people's view, come from the recording.

The most precise means for providing these cues can be provided by binaural,
simulated head recording. Binaural recordings can sound compellingly real.
Trouble is, they sound strange to most people when played over speakers.

[Arny Krueger[_4_]]

"Mxsmanic" wrote in message
...
William Sommerwerck writes:

You couldn't be more wrong. You don't know what you're talking about.

I know exactly what I'm talking about. You have only two cochleas, they
receive only two signals. They are unable to determine direction
unambiguously
unless you move your head. Period.

Intraural timing works at low frequencies.

http://en.wikipedia.org/wiki/Interaural_time_difference

Most people can locate common sound sources in the horizontal plane at ear
height with resonable accuracy without moving their heads.

[Arny Krueger[_4_]]

"Gary Eickmeier" wrote in message
...

"Mxsmanic" wrote in message
...
Soundhaspriority writes:

Mxsmanic's worry that speakers on a salt flat won't sound good is
intuition
that results from experience we've all had.

Actually I don't know if they'd sound good or not, I was just wondering.

All this stuff about speakers sounds extremely complicated. I think
headphones
are a better choice. Headphones give you more control over what is going
into
each ear, and that's what it is ultimately all about, right?

NO. That is what binaural is all about, not stereophonic. Someone stop me
from preaching.

I'm the wrong guy to do that, Gary! ;-)

I already started on the same basic sermon in another subthread.

[Arny Krueger[_4_]]

"William Sommerwerck" wrote in message
...
"Mxsmanic" wrote in message
...
Soundhaspriority writes:

All this stuff about speakers sounds extremely complicated. I think
headphones are a better choice. Headphones give you more control
over what is going into each ear, and that's what it is ultimately all
about, right?

No, what it's all about is accurate reproduction. Headphones eliminate
room
acoustics, but they produce an "in the head" effect, unless you introduce
crosstalk and head-shadowing. Which, oddly, do not appear on any
controller
I'm aware of.

http://www.google.com/patents/US6243476

[Arny Krueger[_4_]]

"Mxsmanic" wrote in message
...
William Sommerwerck writes:

No, what it's all about is accurate reproduction. Headphones eliminate
room
acoustics, but they produce an "in the head" effect, unless you introduce
crosstalk and head-shadowing.

If the original sound is recorded with an artificial head, and then played
back with headphones that introduce the same sound into the ear canals,
the
playback should sound exactly like the original.

It does, but then you have a recording that doesn't sound so hot over
speakers.

The Holy Grail of recording might be finding a way to make both kinds of
recordings at the same time which seems possible, but apparently there is
not enough market for binaural recordings to put them into the mainstream
marketplace.

[Mike Rivers]

On 4/5/2012 1:11 AM, Gary Eickmeier wrote:

No, you have to think of sound waves as a phenomenon that takes some time to
happen. A 50 Hz wave doesn't just "arrive" - it takes 1/50th of a second to
happen. Nor is it just one cycle. I think we all know that drivers would
have to be separated by several feet for anything to be audible at all, that
then it would be for reasons other than time alignment.

HITLER!!!!!!!

--
"Today's production equipment is IT based and cannot be
operated without a passing knowledge of computing, although
it seems that it can be operated without a passing knowledge
of audio." - John Watkinson

http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff

[Arny Krueger[_4_]]

wrote in message
news:17442626.3156.1333555048261.JavaMail.geo-discussion-forums@vbpp14...
On Wednesday, April 4, 2012 7:43:32 AM UTC-4, Gary Eickmeier wrote:
So when does, say, a 50 Hz bass wave arrive?

All sound travels at the same speed, about 1100 feet per second. So if
you're 11 feet in front of a loudspeaker, you'll hear the sound 10
milliseconds after it starts to play.

Actually, waves travel far slower than ideal C in transmission lines, often
close to half speed. I wonder how that works out for real world acoustics?

[Gary Eickmeier]

"Mxsmanic" wrote in message
...
William Sommerwerck writes:

No, what it's all about is accurate reproduction. Headphones eliminate
room
acoustics, but they produce an "in the head" effect, unless you introduce
crosstalk and head-shadowing.

If the original sound is recorded with an artificial head, and then played
back with headphones that introduce the same sound into the ear canals,
the
playback should sound exactly like the original.

A brief read of the literature will show what Bill is saying - binaural is a
terrific idea, but it has its problems too. In-Head Localization is the
chief among them. Loudspeaker binaural solves the head rotation problem but
not the freedom of movement problem - you have to remain glued to the sweet
spot. I have been having a great conversation with the "master" of
loudspeaker binaural recording and reproduction, Ralph Glasgal at
http://www.ambiophonics.org/ . Take a gander over there if you want to
pursue this subject.

Stereophonic sound, encompassing the whole field of surround sound from
loudspeakers, is a much more controversial subject. It is a field-type
system in which both ears are free to hear both - or all - speakers and the
room they are established in, in an attempt to mimic the sound field
produced by the original that was recorded. How to position the speakers,
which radiation pattern and frequency response, how big a room and what room
treatment, how many surround speakers, and on and on are the subject of
great controversy and creativity in the industry and the marketing forces
that support it. Big subject, and in this area there are no "experts," just
a LOT of opinions.

Maybe start another thread if anyone wants to discuss this further.

Gary Eickmeier

[Scott Dorsey]

In article ,
William Sommerwerck wrote:
"Mxsmanic" wrote in message
.. .
Soundhaspriority writes:

All this stuff about speakers sounds extremely complicated. I think
headphones are a better choice. Headphones give you more control
over what is going into each ear, and that's what it is ultimately all
about, right?

No, what it's all about is accurate reproduction. Headphones eliminate room
acoustics, but they produce an "in the head" effect, unless you introduce
crosstalk and head-shadowing. Which, oddly, do not appear on any controller
I'm aware of.

That's merely because the original recordings are made to be reproduced on
speakers.

If they were recorded and mixed to be reproduced on headphones, they would be
quite different.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Mxsmanic wrote:
Soundhaspriority writes:

That one is tough, too. The ear-brain localization system is deprived of
cues provided by the external ear and skull.

There aren't any cues provided by the external ear or skull.

Actually, that's how most imaging actually occurs.

I understand that you don't have any money to buy books, and you don't
have a library nearby, and your brain is damaged and the dog ate your
homework. However, I highly recommend that you scrape together whatever
coins you have left in your pocket and purchase a used copy of "Music,
Physics and Engineering" by Harry F. Olson which really will be a good
introduction to some of this fundamental stuff.

All of the extra cues that are available when listening to sound live come
from moving the head. Wearing headphones is equivalent to listening to sound
with the head rigidly held in one position.

No, not at all. Reflections off the pinnae mean that the frequency response
of your head varies as you move off axis and your brain uses this for
localization. If you get a binaural recording made with a dummy head, the
effect is uncanny and you have accurate height cues and the ability to
localize sounds above, below, and behind you in 3-space. There is some
discussion of this in Olson's book.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Arny Krueger wrote:
wrote in message
news:17442626.3156.1333555048261.JavaMail.geo-discussion-forums@vbpp14...
On Wednesday, April 4, 2012 7:43:32 AM UTC-4, Gary Eickmeier wrote:
So when does, say, a 50 Hz bass wave arrive?

All sound travels at the same speed, about 1100 feet per second. So if
you're 11 feet in front of a loudspeaker, you'll hear the sound 10
milliseconds after it starts to play.

Actually, waves travel far slower than ideal C in transmission lines, often
close to half speed. I wonder how that works out for real world acoustics?

1. Propagation in free air does not result in group delay... all frequencies
propagate at the same rate. And no, ground reflections don't alter this.

2. Group delay really isn't all that audible anyway.

3. Group delay through a typical 2-way speaker system is very high anyway,
often more than 360 degrees at the crossover region, and this would swamp
any acoustical effects if they actually did exist.

4. In a transmission line you can alter speed of propagation of a wave, by
varying air pressure. This is a trick phasing plug designers have used.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[William Sommerwerck]

No, what it's all about is accurate reproduction. Headphones eliminate
room acoustics, but they produce an "in the head" effect, unless you
introduce crosstalk and head-shadowing. Which, oddly, do not appear
on any controller I'm aware of.

That's merely because the original recordings are made to be reproduced
on speakers.

You got it backwards. The processing is needed for conventional recordings.

[Scott Dorsey]

In article ,
William Sommerwerck wrote:
No, what it's all about is accurate reproduction. Headphones eliminate
room acoustics, but they produce an "in the head" effect, unless you
introduce crosstalk and head-shadowing. Which, oddly, do not appear
on any controller I'm aware of.

That's merely because the original recordings are made to be reproduced
on speakers.

You got it backwards. The processing is needed for conventional recordings.

Processing is needed either way, it's just different processing.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[William Sommerwerck]

I understand that you don't have any money to buy books, and
you don't have a library nearby, and your brain is damaged and
the dog ate your homework.

There's a classic Sam Gross "New Yorker" cartoon that shows a Venetian
classroom, ca. 1500. One of the students is explaining why he isn't
prepared: "The Doge ate my homework."

[[email protected]]

On Thursday, April 5, 2012 8:29:38 AM UTC-4, Arny Krueger wrote:
Actually, waves travel far slower than ideal C in transmission lines, often
close to half speed. I wonder how that works out for real world acoustics?

This is outside of my knowledge. Any link to more info?

--Ethan

[None]

"Mxsmanic" wrote in message
...
William Sommerwerck writes:

You couldn't be more wrong. You don't know what you're talking about.

I know exactly what I'm talking about. You have only two cochleas, they
receive only two signals. They are unable to determine direction
unambiguously
unless you move your head. Period.

Tagging "Period" on the end of ill-informed crap doesn't
magically make it true.


You need to leave this group and study sound, sound recording, and sound
reproduction for a while.

In this case, it's simple math, and has no relation to sound, sound
recording,
or sound reproduction.

You can't triangulate a position with just two signals. It's as simple as
that.

But it's not "as simple as that." It's much more complex, and
it involves a lot more than just triangulation. And in fact, triangulation
with just two signals is commonplace. There are so many errors
of ignorance, assumption, and arrogance in your simpleton
misunderstanding that it's hard to know where to start to educate
you, but it doesn't matter, you don't give a **** that you're full of
****, and you don't really want to understand. You just want to
troll. It may be that you just aren't smart enough to understand;
you may truly be as simple as you seem.

A stationary head provides only two signals. If you want more, you have
to move your head.

If you want more, you have to move your head out
of your rectum. But you like it there; you don't want
more.

[Scott Dorsey]

wrote:
On Thursday, April 5, 2012 8:29:38 AM UTC-4, Arny Krueger wrote:
Actually, waves travel far slower than ideal C in transmission lines, often
close to half speed. I wonder how that works out for real world acoustics?

This is outside of my knowledge. Any link to more info?

Terman's "Radio Engineering" talks a little bit about it. If you look in
the Belden catalogue, you can see a column for the percentage of C at which
signals travel down the cable. I only remember the fudge factors, 66% of C
for RG-58, 70% for RG-400. Solid antennas are 10% longer than free wavelength
in vacuum, hollow ones 8%.

Likewise with pressure waves in a fluid medium, the density of the medium
changes the speed of propagation. This is why when you set the notch filters
to kill the resonant modes in the cool morning at the music festival, you
find that in the hot afternoon the resonant modes are at different frequencies
than they started out.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Les Cargill[_4_]]

Scott Dorsey wrote:
wrote:
Soundhaspriority writes:

That one is tough, too. The ear-brain localization system is deprived of
cues provided by the external ear and skull.

There aren't any cues provided by the external ear or skull.

Actually, that's how most imaging actually occurs.

I understand that you don't have any money to buy books, and you don't
have a library nearby, and your brain is damaged and the dog ate your
homework. However, I highly recommend that you scrape together whatever
coins you have left in your pocket and purchase a used copy of "Music,
Physics and Engineering" by Harry F. Olson which really will be a good
introduction to some of this fundamental stuff.


+1 for Olson. Wish I'd had it decades ago.

All of the extra cues that are available when listening to sound live come
from moving the head. Wearing headphones is equivalent to listening to sound
with the head rigidly held in one position.

No, not at all. Reflections off the pinnae mean that the frequency response
of your head varies as you move off axis and your brain uses this for
localization. If you get a binaural recording made with a dummy head, the
effect is uncanny and you have accurate height cues and the ability to
localize sounds above, below, and behind you in 3-space. There is some
discussion of this in Olson's book.
--scott



--
Les Cargill

[[email protected]]

On Thursday, April 5, 2012 1:13:55 PM UTC-4, Scott Dorsey wrote:
Likewise with pressure waves in a fluid medium, the density of the medium
changes the speed of propagation.

Ah, got it, thanks. I didn't realize that happens in transmission line speakers. Though I did know that the air pressure can be so great inside the throat of a high-powered horn speaker that the air's non-linearity can become a factor.

--Ethan

[Arny Krueger[_4_]]

"Scott Dorsey" wrote in message
...
wrote:

This is why when you set the notch filters
to kill the resonant modes in the cool morning at the music festival, you
find that in the hot afternoon the resonant modes are at different
frequencies
than they started out.

Roger that!

Also happens in rooms with poor heating. The room I work in the most had a
history of ineffective heating. The people in the pews had to wear their
coats and I had to retune all of my feedback notches.

Another effect of temperature effects is that acoustic measurements aren't
all that stable. Unseen, particularly in large rooms are drafts and currents
of air with different temperatures. If you set yourself up to make very
careful and stable measurements of acoustic parameters, particularly in
large rooms, you can seen your results wander around right before your eyes
(on the test equipment).

[Scott Dorsey]

wrote:
On Thursday, April 5, 2012 1:13:55 PM UTC-4, Scott Dorsey wrote:
Likewise with pressure waves in a fluid medium, the density of the medium
changes the speed of propagation.

Ah, got it, thanks. I didn't realize that happens in transmission line speakers. Though I did know that the air pressure can be so great inside the throat of a high-powered horn speaker that the air's non-linearity can become a factor.

It's really a total non-issue, except for things like the phasing plugs, etc.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Mxsmanic]

Arny Krueger writes:

Intraural timing works at low frequencies.

http://en.wikipedia.org/wiki/Interaural_time_difference

A time difference will place a source on a circle. Two ears will provide two
circles. The circles will generally intersect at two points, so there isn't
any way to determine which of those two points is the actual location of the
sound source. Simple math.

In three dimensions, it's worse. The circles are spheres, and they intersect
to form a circle, and the sound source can be anywhere on the circle.

Most people can locate common sound sources in the horizontal plane at ear
height with resonable accuracy without moving their heads.

If that were true, it wouldn't be so hard to locate the source of a funny
noise in an engine or car.

In fact, just today I was trying to figure out which of several fans in my PC
is making noise, but it's just too difficult. I need something that can
isolate the sounds directionally, so that I can point and listen.

[Mxsmanic]

None writes:

Tagging "Period" on the end of ill-informed crap doesn't
magically make it true.

Calling it ill-informed crap doesn't magically make it false, either.

But it's not "as simple as that." It's much more complex, and
it involves a lot more than just triangulation. And in fact, triangulation
with just two signals is commonplace.

With two signals in 3D space, the best you can do is locate the sound source
on a circle. In practice the results are worse.

There are so many errors of ignorance, assumption, and arrogance
in your simpleton misunderstanding that it's hard to know where to
start to educate you ...

List them. That would be a lot more persuasive and instructive than some
sophomoric personal attack.

[Mxsmanic]

Scott Dorsey writes:

No, not at all. Reflections off the pinnae mean that the frequency response
of your head varies as you move off axis and your brain uses this for
localization.

That's an inference, not a deduction, and the brain can easily make mistakes
with it. Because of that, it's possible to fool the brain with headphones.

If you get a binaural recording made with a dummy head, the
effect is uncanny and you have accurate height cues and the ability to
localize sounds above, below, and behind you in 3-space.

You can _infer_ that a sound source is at one point or another, but you cannot
_deduce_ its location, because cues that don't involve movement of the head
are unreliable and may be duplicated by multiple sound locations.

[Mxsmanic]

Arny Krueger writes:

The above ignores the fact that the cues in question should, in many
people's view, come from the recording.

Cues that come from a two-track recording are ambiguous. The listener can
infer the location of sound sources from such a recording, if it is made from
real life, but the inferences can easily be wrong.

To eliminate the ambiguity, you need to sweep the radar through an arc (i.e.,
move the head) so that you can correlate changes in sound with changes in
azimuth.

It works for radar, GPS, etc., and the rules are the same for human ears,
because they are imposed by the laws of math and physics.

The most precise means for providing these cues can be provided by binaural,
simulated head recording. Binaural recordings can sound compellingly real.
Trouble is, they sound strange to most people when played over speakers.

I've listened to a few--on headphones--and they sound very cool. The one thing
that is missing is a change in the sound with head movement--that would make
the reproduction indistinguishable from the real thing.

[Mxsmanic]

William Sommerwerck writes:

And how many binaural recordings are available at your local record store?

I have two or three CDs of such recordings somewhere here.

[Mxsmanic]

Arny Krueger writes:

It does, but then you have a recording that doesn't sound so hot over
speakers.

Perhaps, but the whole idea would be to listen to it with headphones.

Personally, I'm not sure why people spend so much time and effort on speakers
when working on improving headphones would make more sense, at least for
recordings that are supposed to sound realistic. Accommodating head movement
is entirely feasible technically today. In fact, you should be able to
dynamically remix 5.1 recordings in a way that would make them very realistic,
if they were recorded originally for that purpose.

The Holy Grail of recording might be finding a way to make both kinds of
recordings at the same time which seems possible, but apparently there is
not enough market for binaural recordings to put them into the mainstream
marketplace.

I imagine most people don't want maximum realism so much as pleasing sound.
And most sound recordings seem to be music, where reproducing the original
sound as it was heard in real life is not necessarily important.

[Mxsmanic]

Gary Eickmeier writes:

A brief read of the literature will show what Bill is saying - binaural is a
terrific idea, but it has its problems too. In-Head Localization is the
chief among them. Loudspeaker binaural solves the head rotation problem but
not the freedom of movement problem - you have to remain glued to the sweet
spot.

You could design headphones with motion sensors and use a multitrack recording
to solve this, though. You need sensors for rotation and translation along
three axes, plus, say, six tracks recorded at equally spaced points on a
sphere. Then you remix the tracks dynamically as the listener moves his head.
Totally doable today, I'm sure.

I have been having a great conversation with the "master" of
loudspeaker binaural recording and reproduction, Ralph Glasgal at
http://www.ambiophonics.org/ . Take a gander over there if you want to
pursue this subject.

I'll take a look.

[Tom McCreadie]

A time difference will place a source on a circle.

Sorry, but a time difference - which is proportional to a distance difference
between the sound source and the two ears - will place the source on a
hyperbola.

Check your Wikipedia for the definition of a hyperbola as expressed in terms of
distance from foci: "A hyperbola may be defined equivalently as the locus of
points where the difference of the distances to the two foci is a constant equal
to 2a, the distance between its two vertices."

We could rephrase that as "a hyperbola is the curve representing all allowable
sound-source locations that would still result in the same constant time delay
(path length difference) being experienced between the ears (or capsules of an
AB mic array)"

[Scott Dorsey]

Mxsmanic wrote:
Scott Dorsey writes:

No, not at all. Reflections off the pinnae mean that the frequency response
of your head varies as you move off axis and your brain uses this for
localization.

That's an inference, not a deduction, and the brain can easily make mistakes
with it. Because of that, it's possible to fool the brain with headphones.

Umm.... _all_ imaging is by inference. Come to think of it, all hearing is
too.

But... you're not actually here to learn about audio, you're here to
deliberately start flame wars. Please go away.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Arny Krueger[_4_]]

"Mxsmanic" wrote in message
...
Arny Krueger writes:

Intraural timing works at low frequencies.

http://en.wikipedia.org/wiki/Interaural_time_difference

A time difference will place a source on a circle.

Nope, a hyperbola http://www.jneurosci.org/content/11/3/722.full.pdf

[Arny Krueger[_4_]]

"Mxsmanic" wrote in message
news
None writes:

Tagging "Period" on the end of ill-informed crap doesn't
magically make it true.

Calling it ill-informed crap doesn't magically make it false, either.

But it's not "as simple as that." It's much more complex, and
it involves a lot more than just triangulation. And in fact,
triangulation
with just two signals is commonplace.

With two signals in 3D space, the best you can do is locate the sound
source
on a circle. In practice the results are worse.

Wrong - its a hyperbola. Reference cited in another post.

[Arny Krueger[_4_]]

"Mxsmanic" wrote in message
...
Arny Krueger writes:

The above ignores the fact that the cues in question should, in many
people's view, come from the recording.

Cues that come from a two-track recording are ambiguous.

They can be, but they need not. Example: Binaural recording.

[None]

"Mrs Maniac" , which his head up his ass,
wrote in message news
There are so many errors of ignorance, assumption, and arrogance
in your simpleton misunderstanding that it's hard to know where to
start to educate you ...

List them. That would be a lot more persuasive and instructive than some
sophomoric personal attack.

Your pigheaded refusal to bother to read the instructional
material to which you have been referred shows that you
have no interest in being instructed. You prefer to be an
ignorant asshole, and it really doesn't matter whether you
think such an accurate assessment is polite.

Pull your head out of your asshole and read some of the
works that have been named in this newsgroup. As long
as you refuse to do that, yet continue to post, you are
essentially bragging about being an ignorant ****head.

Politeness, or lack of politeness, doesn't change those simple
facts, nor does it magically eliminate all the well-known and
experimentally verified effects of the skull, pinnae, ear canals,
etc, and provide stimuli directly to the cochleae which somehow
transmit the information to the rectal lining of your brain. All
of which you could read about if you weren't so proud of being
an ill-informed asshole.

If you continue to make a spectacle of your ignorance, you
have no justification in whining when it's pointed out to you.
Read a book (several have been suggested), or better yet, just
**** off out of here and troll somewhere else.

[John Williamson]

Mxsmanic wrote:
Arny Krueger writes:

Intraural timing works at low frequencies.

http://en.wikipedia.org/wiki/Interaural_time_difference

A time difference will place a source on a circle. Two ears will provide two
circles. The circles will generally intersect at two points, so there isn't
any way to determine which of those two points is the actual location of the
sound source. Simple math.

In three dimensions, it's worse. The circles are spheres, and they intersect
to form a circle, and the sound source can be anywhere on the circle.

Don't forget to allow for the fact that due to the shape of the ear, the
frequency response of each ear differs as the sound source changes
direction, which means that the two points of intersection can be
differentiated by the differing frequency content of the sound at each ear.

We've all had millions of years of evolution and most of us have had a
lifetime's experience of decoding these changes, so as a result, you can
locate any sound quite closely in the 360 degrees without moving our
heads, although some sounds with a long attack and in certain frequency
bands can be (very) hard to locate. Vertical location is more difficult,
but can still often be done, although it may need slight head movement.

Most people can locate common sound sources in the horizontal plane at ear
height with resonable accuracy without moving their heads.

If that were true, it wouldn't be so hard to locate the source of a funny
noise in an engine or car.

In fact, just today I was trying to figure out which of several fans in my PC
is making noise, but it's just too difficult. I need something that can
isolate the sounds directionally, so that I can point and listen.

What you need, both in the case of the engine and the computer, is to
remove the reflecting surfaces and the transmission paths inside the
engine or PC case which are spreading the sound. This is why many motor
vehicle engineers have a stethoscope in their toolbox.

--
Tciao for Now!

John.

[John Williamson]

Mxsmanic wrote:
None writes:

Tagging "Period" on the end of ill-informed crap doesn't
magically make it true.

Calling it ill-informed crap doesn't magically make it false, either.

NO, but when it *is* ill-informed crap...

But it's not "as simple as that." It's much more complex, and
it involves a lot more than just triangulation. And in fact, triangulation
with just two signals is commonplace.

With two signals in 3D space, the best you can do is locate the sound source
on a circle. In practice the results are worse.

If you have a problem doing this with most sounds, then maybe you need
your hearing checked. Problems locating sounds are often an early sign
of approaching deafness or damage to one or both cochleas. Or, more
likely, a build up of wax in one or both ears.

There are so many errors of ignorance, assumption, and arrogance
in your simpleton misunderstanding that it's hard to know where to
start to educate you ...

List them. That would be a lot more persuasive and instructive than some
sophomoric personal attack.

It would be easier to list what you've got right.

""

There you go...
--
Tciao for Now!

John.

[PStamler]

Mxyzptlk, if you really want to learn something about this stuff
(which I kind of doubt), there are several places you can learn it for
free. You might start with Technical Books Online:

http://www.tubebooks.org/technical_books_online.htm

In the audio section, check out books by Norman Crowhurst and G. A.
Briggs. When you're feeling ambitious, download the Radiotron
Designer's Handbook.

These books were written before stereo became common, so some of them
won't talk specifically about how people's perceptions of direction
work (which this thread has evolved into), but you could learn a whole
lot from the books on this site. There are some real classics here.

Peace,
Paul

[Mxsmanic]

Tom McCreadie writes:

Sorry, but a time difference - which is proportional to a distance difference
between the sound source and the two ears - will place the source on a
hyperbola.

A hyperbola contains multiple points, too. So the source is still not
unambiguously located.

[Mxsmanic]

Arny Krueger writes:

Nope, a hyperbola http://www.jneurosci.org/content/11/3/722.full.pdf

I was thinking of absolute rather than relative measurements.

Nevertheless, a hyperbola is just as ambiguous as a circle. Either way, the
location of the source has not been located, just constrained.

[Mxsmanic]

John Williamson writes:

Don't forget to allow for the fact that due to the shape of the ear, the
frequency response of each ear differs as the sound source changes
direction, which means that the two points of intersection can be
differentiated by the differing frequency content of the sound at each ear.

But attempting to locate sound sources in this way involves inference, not
deduction, so it does not reliably and unambiguously locate a sound source.

If this were not true, much of professional audio would have no reason to
exist. If human hearing really could locate sound sources reliably, then
speakers and headphones would sound terribly artificial.

We've all had millions of years of evolution and most of us have had a
lifetime's experience of decoding these changes, so as a result, you can
locate any sound quite closely in the 360 degrees without moving our
heads, although some sounds with a long attack and in certain frequency
bands can be (very) hard to locate. Vertical location is more difficult,
but can still often be done, although it may need slight head movement.

Head movement changes the game entirely. But without it, there can be no
unambiguous localization of sound sources. The more unfamiliar the sound or
situation, the more unreliable inferences will be.

What you need, both in the case of the engine and the computer, is to
remove the reflecting surfaces and the transmission paths inside the
engine or PC case which are spreading the sound.

Not practical. So I need a tool that can isolate the sounds.

This is why many motor vehicle engineers have a stethoscope in their
toolbox.

Yes, or something similar. A plastic tube might even be sufficient.