Originally Posted by davidrmoran
>> I believe the evidence strongly points to direct sound dominating perception
Not clear to me what you mean here by 'perception', but I sense that we are probably done. It is easy enough to show that direct sound to the ear is trivial (unless you are wearing the speakers on your shoulders) to our sense of things with some experiments and also some thought experiments. Imagine playing a piano, or sitting in front of a single loudspeaker say at 2' distance, as the platform where everything is located was moved into a gym, into a closet, into a bathroom, into a field, up into the trees, into a huge anechoic chamber, and then finally back into your listening room with a pass through your kitchen. Write a diary entry on the dozen changes you heard as you played chopsticks or Mozart or boogie-woogie. Or listened to same. The direct sound in all cases was unchanging. What you hear changes dramatically!
By perception in this instance, I mean perception of the anechoic source, which is independent from perception of the acoustic environment that it is within. If you record the piano in each of those different environments and then perform spectral analysis, the balance will vary over the place depending on the environment, yet in most of those instances, we will still hear the timbre of the piano accurately.
Exceptions may be: in the gym if we're sitting so far away that the reverb overwhelms our ability to parse the direct sound from the overall sound-field; and in the closet or bathroom where the direct sound itself is indistinguishable from a high density of early reflections or standing waves. In either of those cases, we cannot accurately gauge the timbre of the source independently from the acoustic effects and we end up hearing a lot of mud instead.
Originally Posted by davidrmoran
>>I sense you have not done the sketch or the maths for playback of a 220Hz oboe tone warming up, how many cycles, how many feet to the near corner and thence to you at your seat including the reflected paths, how much time elapses, etc. etc.
Well, the only near corner in my room is about 5 feet from the nearest speaker and about 14 feet from the listening position, so the total path traveled is between 3 and 4 cycles at 220 Hz. Hence, I said the situation is "borderline" in general and will depend a lot on the speaker, placement, listening position, and room. Another thing I know is that my toed-in and wider-than-typical speaker doesn't send as much energy in that direction. Though, the cabinet directivity drops off pretty rapidly below that frequency. So yes, I've thought about these things quite a bit.
As for the time it takes for "a 220 Hz oboe tone warming up", this is an ill-defined quantity. This highlights a central concept of frequency analysis: there is always a trade-off between temporal and frequency resolution. The time for sine wave at *precisely* 220 Hz to "spin up" is effectively infinite because we have already defined the frequency resolution to be maximal. If we instead concern ourselves with a band of frequencies, i.e. a 1/3rd octave band centered at 220 Hz, then I can give you a rough notion of time it takes for that frequency phenomenon to manifest: just a few cycles in this particular case.
Part of the reason this is important is that an oboe does not produce a sustained sine wave. Chances are, the precise frequency of the tone is fluctuating a bit as is the level. I believe our brains care much more about the attack, decay, release, and various modulations of the pitch, level, and timbre that occur as the note is sustained. All of these things are changes, transient things that manifest in the direct sound first, thus giving our brains something to latch on to and follow. Otherwise, we'd just get lost in the cacophony of the reflected sound field that we are surrounded by.
I would also point out that as far as your argument is concerned, there's nothing special about 220 Hz. If you measure an impulse response in the mid-field or far-field in a typical listening room and apply a window of 30-40 ms, i.e., the time you suggest as the approximate ear integration time, you will see a horrible mess of peaks and dips throughout the frequency range all the way to the very top. So you could ask the same question of 4 kHz or 10 kHz. Now imagine the sound of an oboe playing being convoluted with that mess of peaks and dips, and tell me if you think the result has *anything* to do with what you hear as a listener in that room.
Of course, the impulse measurement does hold a lot of useful information that can be extracted by using the right methods of analysis, but that is a subject for another discussion and probably another thread. I may have already overloaded some other readers with a bit too much technical information here.
Originally Posted by davidrmoran
Interesting phrasing. The usual phrasing is the ear being 'captured' by the first arrival. But not for timbral / spectral judging.
Another experiment that entails a little work. Which I have done (partly!). If direct sound mattered to anything other than localization, a given speaker would all sound mostly the same as you moved it from environment to environment. In a cubical room made of glass, a public library, a rug showroom, a closet, and outdoors. A public shower. A swimming pool. Do a little bit of this work and see what you think. Borrow some dressing mirrors and put them to the sides. of your speakers Then drape the mirrors with heavy carpet swatches or thick wool blankets. Next move the speaker into the corners. Then relocate them on the long wall. Place them so the woofer is equidistant from the three near boundaries (corner), and finally stagger them (this one is a bit subtler).
In most cases, to my ear, almost everything changes, and you can hardly tell it's the same speaker. I am not alone in this finding.
And nowhere is that more true than in the lower midrange, 220Hz. Well, maybe that's a lie. God knows the playback heard in your ear centered on 3k will change enormously. Ditto for 35Hz. Ditto for drum brushwork and rimshots centered on 3k-9k.
Just do the rug-mirror part, and the indoors-outside part.
I agree that this is probably true to some extent at 220 Hz, but is it really true for mid and high frequencies, i.e. above a threshold around about 250-1000 Hz? My understanding of Dr. Toole's work is that above some frequency, we mainly hear the speaker *despite* the room. That doesn't mean that we don't hear the room at all, but rather that the speaker sound and room sound are independently perceived. Dr. Toole, if you are reading, please correct me if I am misreporting your opinion here.
To go back to the piano thought experiment, we can hear it's the same piano no matter what environment we're in, provided that the acoustics aren't so bad as to interfere with the perceptual process. The actual sound we hear is totally different in each case, but the sound that we attribute to the source, the piano in the room, is always the same. Do you not agree?
The reasons above make a strong case for why direct sound dominates both localization and timbre perception even as early reflections modify that perception. If you don't agree with the above, then perhaps we have indeed reached the end of our productive discourse.
Oh, I see you mention 3 kHz. I guess that may be a valid exception, though I'm not sure rimshots or brushes are really sustained long enough to excite the ear resonance much. How about violins? They can hit 3k pretty hard with sustained tones. Though honestly, speaking from experience of playing in string orchestras growing up, I never noticed differences in the sound of live violins that I could not attribute to the acoustics of the room or the skill of the performer(s). OTOH, I think I've only heard two speakers in my life that did the sound of the violin justice: the Revel Salon 2s and my own.