New Age "wine enhancement"

You are witnessing macro effects - that is all you can witness. You can not make the leap from that to claiming there is a particle. The very word is a macro-dimensioned conceit, and has no meaning in the sub-atomic world. It is no more than a rather poor analogy in words we can understand.

d

OK, I'm with you now, Don. It's true that the best description of any QM object is its wavefunction, which is nothing but a mathematical construct and exists over all space. The problem I have is when you say that because all I can witness are macroscopic phenomena (true, but tautological) I cannot claim that there is a particle: all that I'm saying is that we can claim that there is a photon; what word we use to describe it is mere semantics and -- as you say -- there is no word that will adequately describe a photon. Please note, though, that at various points in my career I have been performing QM computations, so I learned long ago to dispense with any attempt to visualize the species I was studying as ultimately misleading and a waste of effort.

Mark Lipton

OK we agree. The problem is that it is far to easy to confuse the label with the phenomenon. And as you conclude - as far as we are concerned, the maths is really all there is.

d

Mike Tommasi wrote, early in the thread "New Age wine enhancement":

Mike, I don't know if that did much good, but thanks.

On the other hand, a recent conversation with someone who had something to do with the history of newsgroups illuminated another angle that I thought I'd mention. My informant described an experiment years ago. A popular newsgroup (with serious subject matter, but attracting a lot of dross) was converted to moderated form. Keep in mind that with newsgroups, just like mailing lists, moderation is pre-facto -- you send the posting to the moderator, who screens it. (Unlike the later, HTTP-based forum tools now popular, which have central content control of course, therefore allow after-the-fact edits.)

An effort was made to keep all irrelevant chat out of the new moderated newsgroup. But the organizers found that a certain proportion of chat is necessary to sustain interest. Even people who'd supported moderation would drift away, otherwise. Other experience supported this observation.

Just food for thought. -- Max

Yes, I enjoyed the exchange between Mark and Don. ;-)

The difference between audio eeks and wine geeks is that wine geeks do not believe the hocus pocus stuff, audio geeks do.

cheers

Mike (former member of the Audio Engineering Society)

Mark,

If I had even an inkling about what QM and NMR are, I'd be glad to attempt an answer! :->)

As for waves resonating, a room can resonate and waves are the result. Likewise for an electrical circuit. In this case, the poster is clearly clueless. These new-agers kill me when they use terms like resonance and "energy" in a way that shows they have no idea what they're talking about.

--Ethan

I really wouldn't be too picky if I were you, Ethan. You use the term resonance when you are actually talking about modes. Easily done, isn't it? ;-)

d

I'd agree with you, but I'm too busy aligning my chakras with specially tuned quartz crystals and placing the finishing touches on my Orgone box to spare the brain cells needed to do so.

Mark Lipton

Well he did mention Quantum Mechanics by name already, and NMR I assume is Nuclear Magnetic Resonance. It's not too hard to Google these things if you really wanted to know. Obviously not I guess.

MrT.

Mark,

Okay, thanks.

What's that have to do with wine? :->)

--Ethan

Don,

Don't get me started! :->)

Seriously, a mode is a propensity to vibrate. There's no wave or resonance until the mode is excited. Sort of like an EQ set to a narrow boost, but with the power switch turned off. I'd say with no signal rather than turned off, except the residual input noise is a signal so there's still some resonance. Versus a room mode that is silent until something in the room makes a sound at or near the mode's frequency.

--Ethan

But they lack the vital central component of resonance - energy storage in two complementary forms, with periodic transfer between those two forms. Springs and masses do this between kinetic and potential energy. Electronic circuits do it between magnetic and electric fields. Rooms do it (in Helmholz resonator mode) the same way as springs and masses.

But modes don't do this. All that happens is that waves travelling in two directions will add in some places and cancel in others. So the biggest "gain" you can see is 3dB at any point, while dips can approach infinity. This is radically different behaviour from resonance. For example, there is no meaningful Q factor associated with a mode.

If you want to simulate modes with eq, don't set for narrow boost - that is entirely the wrong thing. Set for narrow cut, with several dips at harmonically related frequencies.

I could go on, but I won't. I'm sure you can see what I'm getting at.

d

Don,

Not sure where you draw the line between "rooms" and "modes." A room does resonate. In that case it seems to me the air is both the mass and the spring.

You can DEFINITELY have peaks larger than 3 dB. First, a single reflection off a boundary (comb filter) gives a 6 dB peak, not 3 dB. But in a real room multiple reflections from multiple boundaries can combine to give a total peak larger than 6 dB. Since the response in a smallish room varies dramatically over distances as small as a few inches, even at very low frequencies, it's tough to say for sure where a peak ends and a null begins.

Actually, I don't see what you're getting at. Room modes, when excited, are like an EQ boost with a fairly high Q. This is easily seen in waterfall plots such as this one:

--Ethan

I'm talking about a Helmholz resonance, where the mass of air in - say

- a doorway moves in and out of the room, using the air inside the room as a spring. When the air is all the way in or out, the energy is held in the compression. When the air is moving, the energy is held in the movement. That IS a resonance - it has the two energy-swapping phases.

You are right, my maths was all over the place. But the peaks are never sharp. Nulls, on the other hand are incredibly sensitive to position. This because they are caused by phase cancellations. The peaks are simply phase additions. There is no energy storage going on

- hence no resonance.

I see why you would conclude that, but high Q is not what is going on there. They look peaky simply because they are close together. The important part of this, though is really the places where cancellations occur, not the reinforcements.

Look, you have a really good video on comb filtering and how it happens, and why it happens. This is simply a limit case of that phenomenon. You only confuse things when you try to describe it as a resonance.

d

Don,

Yes, agreed.

Look at the GIF file I linked to again and tell me those peaks are not sharp! Then look at the ringing trails and tell me there's no resonance. Yes, there is resonance, and it's due to the wall-wall (or floor-ceiling) spacing reinforcing a wave repeatedly. It's easy to calculate the frequency of the resonance from the spacing between boundaries.

I think both are important. A resonant peak that sustains bass frequencies makes a muddy mess of bass notes, as some notes linger and mask subsequent notes. Resonant peaks also impart their frequency onto nearby bass notes that excite them, often making bass notes sound out of tune even when they're not. That is, if a room has a strong resonance at 112 Hz, every A bass note will sound sharp in that room.

I do agree that nulls are a big problem too, and probably worse than nulls. The most common room acoustics problem I hear is from people who make a mix that sounds great, then they play it in their car or somewhere else and the bass is greatly exaggerated. This is because there's always one or more deep nulls at the mix position, somewhere between 80 and 150 Hz, so when mixing the person adds too much bass EQ to compensate.

--Ethan

No, that truly isn't resonance - it is reverberation, which is an entirely different thing. The reverberation is reinforced at certain frequencies because things are arriving in phase. I promise you this is an entirely different phenomenon to resonance. The tails are not Q related - you are witnessing mode collapse. And unlike Q, you can't rely on them to collapse at a given rate - measure ten times, and you will get ten different answers.

But what do you mean by a room having a resonant peak at 112Hz? Move a couple of feet and you won't hear the note at all.

Nulls are a disaster in a mixing room. You find yourself winding up the eq to hear a note at proper volume, then when you play it somewhere else you end up with the cones hanging out of the bass speakers. At the very least you need to be pushing your chair back and forth to hear what is really there.

d

Don,

I promise you are simply wrong on this point. :->)

Small rooms don't even have true reverberation. Real reverb builds over time, but small rooms have a collection of individual reflections with each decaying quickly. Small rooms also have modal ringing, which is the resonance I keep referring to. Google "room resonance" if you don't believe me. This is Physics 101 so I'm really surprised to see you dispute that rooms resonate!

They ARE related to Q. As bass traps are added to a room, three things happen to the modes as observed in a waterfall chart:

1) The ringing times are shortened. 2) The mode Qs are lowered. 3) The mode frequencies shift down in frequency slightly.

The link between 1 and 2 above indicates resonance. Here's a pair of graphs for the same room I linked above, and these show the room with and without bass traps:

You can clearly see all three of the above parameters change.

Exactly.

--Ethan

In those graphs I see exactly what I expected to see. The modes collapse more quickly because there isn't so much energy returned into them by the walls. But because there is no energy transduction - it remains solely in the wave - there is no resonance.

The big effect is on the nulls - the peaks flatten out in consequence of the nulls filling in.

The frequency drops slightly because the room is effectively lengthened by the presence of an absorber, in which the speed of sound is reduced.

Here's a thing I'd like you to discuss. Comb filtering. If you plot the frequency response of a speaker close to a wall, positioned as in your comb filtering demo, it exhibits peaks and dips in the frequency response because at some frequencies the waves add, and at others they cancel. Do you regard the high spot between those dips as a resonance, with a Q, and all the usual good resonant stuff?

Your answer to that will tell me if there is any chance that we can agree on the rest.

d

Let's make the experiment even simpler. Consider a system which has two signal paths through it: One path is direct, the other path is delayed by 0.2 milliseconds and has a

6 kHz low-pass filter with a slope of 48 dB/octave. The outputs of these two paths are summed linearly into a single output.

Now, consider a second system, which consists of a linear path with a single series circuit consisting of a an inductor and a capacitor whose values are such that the value of 1/sqrt(L*C) is about 16,000 radians per second.

On examining the frequency response of either system, they exhibit a flat response up about 5 kHz, where there is a sharp null, and then they are essentially flat above that frequency.

Question: As they can exhibit essentially identical frequency response, are they both resonant systems?

Why or why not?