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This is an extraordinarily tedious, unnecessarily argumentative and extremely academic thread of no practical relevance to the average SOS reader...

...but if those participating feel they are gaining something constructive from it, that's fair enough. Thankfully, the ratio of views to replies is extremely low in comparison to the norm for the SOS forums, so it's not wasting too much bandwidth.

However, I think I need to respond to Paul's comments since he mentions me specifically -- and I already noticed Eric tried to draw me in earlier with similar notices...

Quote Paul Woodlock:

We've had TWO LONG threads ( related ), and as yet NO ONE has been able to explain the cueball/modes analogy.

The cue-ball analogy has been explained perfectly well as far as I can see, and I don't understand why you are unable to move on.

Quote:

Even Ethan and Hugh, who originally said it was a sound ( no pun itended ) explanation of modal behaviour havne't been able to explain it.

For heaven's sake! The path of a cue ball on a pool table was likened to the ray concept of travelling sound waves, and used purely to differentiate the fundamental difference between axial and tangential modes. That's what analogies are for: to liken the unfamiliar to the familiar, to help decribe some limited aspects of an unfamiliar concept or behaviour.

Once the concept of travelling sounds waves in a confined space are understood, (using the cue ball analogy if it helps) then the additional complexities of low frequency behaviour, and the mutual interaction of LF travelling waves in a confined space to create 'stationary waves' can be explained (if necessary). But as we all know, this topic area quickly gets extremely complicated, and not least because of the three-dimensionality involved.

THE CUE BALL ANALOGY IS NOT A COMPLETE OR EXHAUSTIVE EXPLANATION FOR STATIONARY WAVES: IT IS A USEFUL TEACHING AID TO HELP A NOVICE TAKE A FIRST STEP ALONG THE WAY...

That was the concept in which it was used first on this forum; that is the context in which I support its use; and that is the context in which many other reputable acousticians use it (or similar) analogies. What is the problem?

Quote:

Therefore, I can only conclude that the explantion of modes with a cue-ball model is really quite wrong, and in fact 'Beginners' in particular shouldn't be mislead by this model.

Forgive me if my cynism has come to the fore once more, but this really does look like an attempt either at childish point-scoring (again), or to prolong an argument purely for the sake of it. Grow up! Move on!

Go finish your studio and let's return to discussing more practical and helpful issues of relevance to the SOS readership on this forum. Please

hugh

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Technical Editor, Sound On Sound

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