[*Scotty*]

The complexity of the wave does not change how fast it propagates through the air.  Regardless of the frequency for which you solve the equation the speed of sound will remain the same. It is a constant. This is basic high school physics. Do the math and you will see that the answer is a simple one.( " It is important to note that the sound speed in air is determined by the air itself. It is not dependent upon the sound amplitude, frequency or wavelength." ) See link  http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe.html#c1
Scotty

[opaqueice]

You'll find the Heyser reference (and 78 others) in The Wood Effect; $20 + 2, should you care to learn the truth.

I'll spend my $20 on a new CD, thank you kindly.  And I think I'll choose it based on the music, not the number of mics used to record it....

[opaqueice]

The absolute phase is bull shit.

Wayner, it's not quite as bad as that.  Some instruments - the trumpet is a good example - really do produce direct (not reflected) sound with a definite polarity.  Here's an example: http://www.ugcs.caltech.edu/~tasha/Images/myTrumpetC261Zoom.jpg .  I don't think that's an actual recording, but real recordings look quite similar - and the waveform doesn't change because of distance from the source, scotty is right about that.  On the other hand you're right that reflections will mess that up - reflections off a lower impedance interface (into another room, for example) invert the polarity of sounds. 

In any case, as you can see, flipping the wave upside-down will change it.  The point is that in the actual sound positive voltage corresponded to either compressions or rarefactions (I'm not sure which, but we could find out).  So when you send that waveform to a speaker, the cones will either move in such a way so that they compress the air in the room when the trumpet did (that's the correct polarity) or rarefy it when the trumpet compressed it (that's the wrong polarity).

At least that makes sense for a box speaker....  for a planar or dipole it's much less clear, since then the polarity of the sound wave produced will depend on where you're sitting! 

[Wayner]

At one point in human history, we used to think that light was one wave, one wavelength. It wasn't until recently (from a hisitoric point of view) that light was discovered to be made of many components, many colors with different wave lengths.

I believe the same applies to sound. Many speaker manufactureres believe that high frequencies travel faster than lower frequencies and even off-set their high freq. divers to compensate for what they believe is going on.


Wayner

[opaqueice]

I believe the same applies to sound. Many speaker manufactureres believe that high frequencies travel faster than lower frequencies and even off-set their high freq. divers to compensate for what they believe is going on.

The speed of sound in air is independent of frequency to an extremely good approximation, which breaks down only at frequencies far above audible.  That's been understood theoretically and experimentally verified for 150 years at least.  I'd be shocked if any speaker manufacturers mistakenly believe otherwise.

But you made some good points before - particularly problematic for someone that believes in "absolute polarity" is the fact that (some) reflections invert polarity.  Especially when many venues (concert halls, for example) are designed so that 90% of the sound you hear has been reflected at least once!

[clarkjohnsen]

I have to debate the existence of "Absoulte Polarity" as there is no sound that is of a singular frequency.

Part two of that sentence is just a truism, plus it does not follow logically from part one.

What you're (actively?) ignoring is that instruments have unique attack transients, especially when struck. It is these, not the steady-state behavior, that concerns us here.

Also, the human element (the ear) cannot react to a higher frequency as easily as a lower frequency because of the pure speed involved.

Again with the steady-state argument.

That is why speaker manufacturers can put a tweeter out of phase (to conmpensate for x-over network design) because the frequency is too fast for the ear to benchmark an in or out of phase condition.

Oh no it [the ear] isn't! (Well, I don't know about yours...) The reason manufacturers do put drivers out of phase, is to produce flatter amplitude-response curves -- which are a selling point to those of the steady-state persuasion.

The ear could more easily detect it at lower frequencies, but not with out the help of another low frequency driver that is out of phase with the first.

Pure assertion, and unproven, and likely wrong too.

[clarkjohnsen]

You'll find the Heyser reference (and 78 others) in The Wood Effect; $20 + 2, should you care to learn the truth.

I'll spend my $20 on a new CD, thank you kindly.  And I think I'll choose it based on the music, not the number of mics used to record it....

You again.

Then one must wonder what you're still doing on Audio Circle -- and arguing futilely against established science.

As to how to spend one's money, I spent mine researching, writing and publishing a book to set the record straight (although you're not having that).  You see, I already have 40,000 records and 1200 CDs to nurture my musical life.

[Wayner]

Wow, Clark, your such an impressive dude. 40,000 LPs huh, how do you ever find the time. Write books do ya, sweet. I'm glad I finally found the expert on the final word in sound. You are the man!

I suggest using (something made out of paper) for firewood during these coming cold winter nights, listening to your 40,000 albums..........

[clarkjohnsen]

Wow, Clark, your such an impressive dude. 40,000 LPs huh, how do you ever find the time. Write books do ya, sweet. I'm glad I finally found the expert on the final word in sound. You are the man!

Never said such a number of LPs. Again you are making untoward assumptions. How do you not see that?

Your sneering is not incongruent with your approach to physics.

I suggest using (something made out of paper) for firewood during these coming cold winter nights, listening to your 40,000 albums..........

Begone!

[miklorsmith]

Is trying this out for oneself as easy as flipping speaker leads?

[Russell Dawkins]

It is - but, given the time lapse involved in that method you would in my estimation have to have a very revealing system and very acute hearing to tell right from wrong that way. The almost-never-practical ideal would be to have some form of remote control (even wired) so the change could be made from the listening position.

[miklorsmith]

So it's really an academic question for most folks then?

[Russell Dawkins]

I would say yes, but only in the way most tweaks might be considered academic in light of the massive differences choice of speakers and their proper placement in the room can bring about!

[Wayner]

You'll find the Heyser reference (and 78 others) in The Wood Effect; $20 + 2, should you care to learn the truth.

I'll spend my $20 on a new CD, thank you kindly.  And I think I'll choose it based on the music, not the number of mics used to record it....

You again.

Then one must wonder what you're still doing on Audio Circle -- and arguing futilely against established science.

As to how to spend one's money, I spent mine researching, writing and publishing a book to set the record straight (although you're not having that).  You see, I already have 40,000 records and 1200 CDs to nurture my musical life.

 

[clarkjohnsen]

Is trying this out for oneself as easy as flipping speaker leads?

Yes. But all of them!

Also for material pick something simply recorded and minimally orchestrated. Listen for the fingers on the strings (guitar) or the splash on a cymbal. Trombones are better for this than French horns.

And you speakers must not be phase incoherencers.

Go back and forth until you get it.

The first cut I ever tried it on was, ironically, Starting Over.

clark

[clarkjohnsen]

It is - but, given the time lapse involved in that method you would in my estimation have to have a very revealing system and very acute hearing to tell right from wrong that way. The almost-never-practical ideal would be to have some form of remote control (even wired) so the change could be made from the listening position.

Regrettably I have heard only one remote control (or switch of any kind) that does the trick as well as swapping wires. That was on an Audio Alchemy DAC.

clark

[woodsyi]

And you speakers must not be phase incoherencers.

clark

Classic audio statement. 

[andyr]

So it's really an academic question for most folks then?

Yes - folks that don't have a "phase inversion" switch on the phono stage/CDP, that is.

Flipping speaker leads is liable to lead to shorting out your amp! 

Regards,

Andy

[miklorsmith]

Make sure it's really cranking before the swap for maximum effect, eh?   

[stereocilia]

I can tell you from experience it’s easy to see the effect of polarity when measuring the auditory brainstem response.  However, I would not conclude from this that it is important to preserve it.

A little background:  The auditory brainstem response (ABR) is a physiologic (as opposed to behavioral) measure which uses scalp electrodes to record the neurological response from acoustic stimuli.  Most universal newborn screenings use a version of this method.  It’s easiest to record an ABR using a series of acoustic clicks because the whole cochlea responds at the same time.  It’s also easier to measure when the patient is asleep because the electrical noise from muscle movement is much lower.

 I don’t want to go into measurement details but I can tell you that the waveform resulting from using compression clicks looks different from the one using rarefaction clicks.  Most people, by the way, have clearer wave morphology from rarefaction clicks.  Honestly, it’s not exactly clear to me why this is the case.  It may be purely physiologic, or it may be purely that the two stimuli are not equal in all respects but polarity.  I mean, the standard issue Telephonics TDH-49 headphone ain’t perfect.  Most often, the series of clicks alternate between compression and rarefaction to average the two resulting waves together.

It is my understanding that the cochlea and some of the nuclei further along the chain preserve polarity information, but it is lost by the time it reaches the brain.  I think it gets exchanged for location information when the two ears are compared to each other.

The point is, I think it’s interesting that an objective physiologic measure shows a difference --every time.  But at the same time nobody I know of can actually hear the difference.  Maybe some of you guys can.  I can’t.