Uh, no. Not even the room correction buried deep inside your windows 10 box is that simplistic. Furthermore, the goal of room correction has several components.It is a triumph of measurement over logic. It is based on a vague, unstated assumption: that humans are purely frequency content analysers and that they can't distinguish between direct sound, reflections and reverberation; so as long as the contents of an FFT window more-or-less give the right proportions of 'frequency response stuff', it will sound perfect.
Again, multiply wrong. First, even if one did correct the "whole signal" the time domain cues would remain in the reverberent environment, and localization would proceed apace. You're ignoring the very first basis of the ear's function, which is as a time/frequency analyzer. No room correction algorithm I've studied even comes remotely close to the kind of behavior you seem to think room correction is designed to do.Logic and common experience tells us that this cannot be true, otherwise we would not be able to hear the directions of sound sources in reverberant environments, and people's voices would sound different as we walked from outside to inside.
Again you reach this conclusion because you fail to consider the time domain issues in hearing. It's just wrong, and proper "room correction" does what's intended, and not the opposite. Your conclusion is counter to fact, and is based on many faulty assumptions and a huge leap of faith rather than proper logic.We have evolved, then learned all our lives, to distinguish between a sound source and reflections (a.k.a. 'the room'); we do it expertly and without conscious thought. In our hearing we are not eliminating the room, but we are distinguishing between the source and the room. If we change the sound source to fit some notional 'target curve' it will sound 'changed' but the room will sound just the same! - the opposite of what is intended.
Confusion arises because real speakers are often not very neutral sources, with odd directivity at different frequencies. This cannot be corrected, but it can be compensated for to make the speaker sound subjectively better. The room cannot be corrected, but the speaker in that room in that particular placement may be improved subjectively if there is some understanding of what is going on. Calling it 'room correction' is an indication that that understanding is absent...
Uh, no. Not even the room correction buried deep inside your windows 10 box is that simplistic. Furthermore, the goal of room correction has several components.
1) reduce level in places where the room stores too much energy at low frequencies.
2) make the DIRECT signal accurate at medium/high frequencies (let's not talk "schroeder frequency" here, that's a different issue).
And that is accommodated even in the W10 method.
Again, multiply wrong. First, even if one did correct the "whole signal" the time domain cues would remain in the reverberent environment, and localization would proceed apace. You're ignoring the very first basis of the ear's function, which is as a time/frequency analyzer. No room correction algorithm I've studied even comes remotely close to the kind of behavior you seem to think room correction is designed to do.
As to people's voices sounding different, actually, they do, as they naturally should, as we move and they move, and that part of adaptation is learned at a young age. You don't notice the difference because it's expected. You only notice when it doesn't happen. Wandering around an anechoic room with some big flat panels blocking direct sound will make this clear apace.
Again you reach this conclusion because you fail to consider the time domain issues in hearing. It's just wrong, and proper "room correction" does what's intended, and not the opposite. Your conclusion is counter to fact, and is based on many faulty assumptions and a huge leap of faith rather than proper logic.
And, to some extent, true. Perhaps "source correction" would be better, because in position, speaker level, time delay can be corrected to a very, very high-accuracy extent. Correcting for speakers with moderately different amplitude and phase response, likewise. So, no, let's not quite say that the "room can not be corrected", some low-frequency reflections can be mitigated, after all, and that is often a thing of great value. Speaker distance can be fixed to an astonishing degree, as can differences between speakers, including those due to acoustics of reflective objects, walls, etc, near the speaker.
"Room Correction" is not completely right, but a good room, corrected, will always be better than a good room, left alone.
@j_j , thanks for your comment to @Cosmik ’s ideas.
You wrote:
«Room Correction" is not completely right, but a good room, corrected, will always be better than a good room, left alone».
That made me curious. Do you speak of your own experience or a broader set of research efforts?
And am I wrong if I interpret you as having a more open stance on digital room compensation than @Floyd Toole ?
He's also right that you want to fix the direct sound, and that speakers should be both power-flat and direct-flat if you can manage it, which is an interesting problem at low frequencies that requires that the room match the speakers and their effective directivity at low frequencies.
...which is an interesting problem at low frequencies that requires that the room match the speakers and their effective directivity at low frequencies.
Of all the things to accuse me of!You're ignoring the very first basis of the ear's function, which is as a time/frequency analyzer.
...
Again you reach this conclusion because you fail to consider the time domain issues in hearing.
Yes, this is the binaural hearing system in action - they are called binaural beats, essentially the 'phantom image' being swept rapidly between the ears.Ear/Brain etc...
I was surprised when I created a file with 400Hz in the left channel and 405Hz in the right channel, put on headphones, and heard the 5Hz beat, which didn't exist in either ear, nor in the air.
Hi JJ. Just an addition.
You said: "the ear's function, which is as a time/frequency analyzer". That is a good simple description, but humans have two ears - i.e. binaural hearing - which are active full time thereby adding : direction, spaciousness, envelopment, binaural discrimination, precedence effect, and more to the list of auditory capabilities.
Can you explain what you mean by "the room match[ing] the speakers and their effective directivity at low frequencies"?
Thanks!
Pretty much exactly. There is another gotcha, in that corrections higher in frequency limit the space the correction applies to, if they are too detailed.The challenge is to embed within the EQ system the intelligence to ignore measured aberrations that are not audible problems and focus on those that are, and that includes the ability to address or ignore the effects of reflected energy arriving from different directions, at different times and amplitudes. The fact that the audibility of delayed sounds varies enormously with the temporal structure of the sound is a separate problem overlaying it all (Figure 7.29), and music and movies are ever changing.
And much more of it is in my book. The reality I see is one in which only high resolution (e.g.1/20-oct) anechoic measurements (the spinorama consists of a database of 70 curves) can adequately reveal the timbral accuracy, lack of resonances, and directional properties of the sound source.
If one starts with a timbrally neutral speaker with well-behaved directional properties the rest is made much, much easier.
Which is why I say "room correction" can be beneficial to decent or good rooms. If a room stores too much energy, it stores too much energy. Adding more doesn't help (to correct dips at the listening position), and remove energy (again to fix peaks at the listening position) does (*&(& all for the time hangover.Listeners can adapt to, and to a significant extent "listen through" live performance venues and playback venues. There are limits, of course, and it is up to research to reveal the issues and the magnitudes above which intervention is required. We have some of the answers. In many cases only physical acoustic treatments will suffice.
There is no dominant "direct" sound in the normal sense because at all resonance frequencies the energy builds at a rate determined by the Q, and correspondingly decays.
Of all the things to accuse me of!
I'm practically the only person here who talks about human hearing as a time/frequency analyser and who is not completely taken in by the frequency domain-only way of thinking. Just check back on my posts - I drive everyone mad by continuously pointing out the time domain as well as the frequency domain.
For example, I have only just been discussing the issue of the inverted backwave from open baffle speakers. I am the only person who points out that it is not a good idea for time domain reasons.
(Something tells me you'll find a way to disagree with me on that point, though...)
I understand that part of @Cosmik's criticism of room correction EQ is that he views it as a case of theory-following-practice and that this has resulted in proponents looking for justifications for what may be misconceptions.
What is its history? I tended to believe that it was a domestic application of the use of graphic equalisation in live sound reinforcement -- the tuning of a system by ear to mitigate problems such as resonances and microphone feedback, etc. Thus we saw the fashion of home hi-fi graphic equalisers with so few bands that really they were little more than somewhat technical-looking tone controls. Was that based on theory or the idea that what the professionals use must be good for the home, too? Some trickle-down from professional audio practice to the dosmetic listening enviroment is natural but some is misguided (e.g. "they use an external master clock so I need one, too").
Of course, DRC is now much more sophisticated and much theory and measurement has gone towards explaining its benefits. I like to believe that as the theory develops, the misconceptions will atrophy and best practice will be validated.
Yes, this is the binaural hearing system in action - they are called binaural beats, essentially the 'phantom image' being swept rapidly between the ears.
Fortunately the world has decided that omni woofers are to be the norm. Even most "full bandwidth" dipole speakers transition to monopole bass drivers. I think dipole subwoofers have joined the dodo bird, as they should. There are a couple of cardioid woofers out there somewhere I think.The interaction between the DI of the speaker and the resonances of the room can be "interesting". Having the room have a peak where the power response of the speaker rises vigorously as a result of the DI changing can be "interesting". Not necessarily in a good way, mind you.
[/quote][/QUOTE]Pretty much exactly. There is another gotcha, in that corrections higher in frequency limit the space the correction applies to, if they are too detailed.
But that is the dual of "not audible problems", of course. This is where looking at the time/frequency response of the ear is absolutely critical.
Fortunately the two are not terribly contradictory. They can be in the 300-800 Hz range. We luck out on the time/envelope confusion around 1kHz to 2kHz, and above that, early arrival saves us.
Personally, I would suggest 1/3 ERB spacing. This results in 90 or so bands.
I would say "the rest is made possible". If a speaker has no near-zeros, and has a smooth DI, yes. This is where high-power crossovers with phase shift (yes, corrected, etc, assume "done right" here) can be problematical due to the phase response around the crossover point. Still, it is possible to not do this too poorly, I agree.
Which is why I say "room correction" can be beneficial to decent or good rooms. If a room stores too much energy, it stores too much energy. Adding more doesn't help (to correct dips at the listening position), and remove energy (again to fix peaks at the listening position) does (*&(& all for the time hangover.
One can separate out such analytically, with special stimulii and a fair amount of work, but as far as the ear is concerned, that's about it.
But again, analyzing with the ear's time/frequency response in mind is a great start.
Any woofer or subwoofer I have ever encountered does not change its power response "vigorously" - they are minimum-phase systems that are quite well behaved. However, room modes/standing waves do change dramatically with location of the ears or mic. That is the problem to be addressed. Mode cancelling/attenuation using multiple subs greatly simplifies the situation, but only when the budget allows. Good news is that with multiple subs the total system efficiency rises, so they can be smaller subs.