Well perhaps not immediately. Having often heard stereo reproduction in anechoic and hypoechoic environments, I didn't notice any deleterious effects for stereo. What would those be?
Source width can be altered with phase tricks. That can be done in the recording or in playback, sometimes by accident.
Gaming and VR often use tricks like that.
This is simply not true. Toole often used this term applied to loudspeaker reproduction.
It bothers me that you keep describing the LF information in stereo channels but then you finish with implications of the whole spectrum. This simply isn't the case. I don't worry too much about the LF stereo problems in real small rooms because these rooms act modally and reflections per see are not relevant - they happen in a time frame too short for our hearing to even detect them. The theoretical comb filtering of central images simply won't occur perceptually in a small room at LFs simply because the ear will integrate the sound from many many reflections thus nulling out the comb filter. Now at higher frequencies where the ear can analyze a reflection and the direct field as separate events there will be a comb filter or more specifically an image shift and coloration. But we absolutely must separate perception in a small room between LFs and HFs as the two things act completely different. In large spaces they are not separate and we can combine the two regions into a single perception.
I too have heard stereo in an anechoic chamber. It's not pleasant, but the "flaws" that you allude to were not that evident.
"This is simply not true. Toole often used this term applied to loudspeaker reproduction."
I have not seen it expressed in such a manner and given its dependence on the recording format and how it is replayed, I find it hard to see how any generalisation is possible.
But adopting your previous method of discussing my posts, lets look at what you said:
"It bothers me that you keep describing the LF information in stereo channels but then you finish with implications of the whole spectrum."
...The impression of space and any envelopment discerned from a recording is, firstly, predominantly a low frequency phenomenon and, secondly, reduced because of the inherent LF reduction in the dipolar S channel information.
"This simply isn't the case. I don't worry too much about the LF stereo problems in real small rooms because these rooms act modally and reflections per see are not relevant - they happen in a time frame too short for our hearing to even detect them. The theoretical comb filtering of central images simply won't occur perceptually in a small room at LFs simply because the ear will integrate the sound from many many reflections thus nulling out the comb filter."
...That is exactly what I have been saying. Conventional stereo reproduction requires those reflections that one might also seek to attenuate in order to enhance imaging. There is also relevant information in the LF S channel that is seldom heard because it is attenuated regardless of any room modes (but obviously ignoring any anti-resonances).
"Now at higher frequencies where the ear can analyze a reflection and the direct field as separate events there will be a comb filter or more specifically an image shift and coloration."
...Did I say any different?
"But we absolutely must separate perception in a small room between LFs and HFs as the two things act completely different. In large spaces they are not separate and we can combine the two regions into a single perception."
...Exactly. And efforts made to enhance one can compromise the other. Better to first remove the need to enhance the low frequency room contributions IMHO.
"I too have heard stereo in an anechoic chamber. It's not pleasant, but the "flaws" that you allude to were not that evident."
...I cannot argue with your perception, but the thinning of centrally-panned vocals when one switches from compensated stereo to conventional stereo has been immediately recognised by everyone I have ever demonstrated it to. And as you have described, it is only the response of the room that compensates for what is "not pleasant" in more normal conditions.
I have not seen it expressed in such a manner and given its dependence on the recording format and how it is replayed, I find it hard to see how any generalisation is possible.
But adopting your previous method of discussing my posts, lets look at what you said:
"It bothers me that you keep describing the LF information in stereo channels but then you finish with implications of the whole spectrum."
...The impression of space and any envelopment discerned from a recording is, firstly, predominantly a low frequency phenomenon and, secondly, reduced because of the inherent LF reduction in the dipolar S channel information.
"This simply isn't the case. I don't worry too much about the LF stereo problems in real small rooms because these rooms act modally and reflections per see are not relevant - they happen in a time frame too short for our hearing to even detect them. The theoretical comb filtering of central images simply won't occur perceptually in a small room at LFs simply because the ear will integrate the sound from many many reflections thus nulling out the comb filter."
...That is exactly what I have been saying. Conventional stereo reproduction requires those reflections that one might also seek to attenuate in order to enhance imaging. There is also relevant information in the LF S channel that is seldom heard because it is attenuated regardless of any room modes (but obviously ignoring any anti-resonances).
"Now at higher frequencies where the ear can analyze a reflection and the direct field as separate events there will be a comb filter or more specifically an image shift and coloration."
...Did I say any different?
"But we absolutely must separate perception in a small room between LFs and HFs as the two things act completely different. In large spaces they are not separate and we can combine the two regions into a single perception."
...Exactly. And efforts made to enhance one can compromise the other. Better to first remove the need to enhance the low frequency room contributions IMHO.
"I too have heard stereo in an anechoic chamber. It's not pleasant, but the "flaws" that you allude to were not that evident."
...I cannot argue with your perception, but the thinning of centrally-panned vocals when one switches from compensated stereo to conventional stereo has been immediately recognised by everyone I have ever demonstrated it to. And as you have described, it is only the response of the room that compensates for what is "not pleasant" in more normal conditions.
This isn't true either.
Maybe the reduction in S channel LFs is the reason that most bass on stereo recordings is nearly mono. But again, that doesn't matter since at LFs in small rooms we are dealing with modes and steady state conditions because of our hearing limitations. All that matters is the LF steady state sound field, which is easily adjusted to be smooth and whatever gain one wants via DSP. Of course, multiple LF sources adds a significant advantage here as well.
What ad hoc posted sounds right. Because in an anechoic space you would only get direct sound. So then its the early and late reflections and their position and timing that effects the spaciousness and gives us clues of size and scale.
I would assume the longer the rft the more sense of size you have. Also side reflections give a sense of width and rear reflections depth.
Theres also the issue of flat surfaces vs diffusers, the latter I assume would preserve the frequency response better. Assuming your room isn't a giant pipe then maybe a diffuser is better. At the end of the day its the sense of breadth and space that can make speakers better than headphones imo.
I already brought this up and got no "bites", so last time, how does the speaker off axis response figure in to this? If its not good then it might be better to absorb than diffuse. Why do some speakers seem to tolerate being faced away better than others?
I would assume the longer the rft the more sense of size you have. Also side reflections give a sense of width and rear reflections depth.
Theres also the issue of flat surfaces vs diffusers, the latter I assume would preserve the frequency response better. Assuming your room isn't a giant pipe then maybe a diffuser is better. At the end of the day its the sense of breadth and space that can make speakers better than headphones imo.
I already brought this up and got no "bites", so last time, how does the speaker off axis response figure in to this? If its not good then it might be better to absorb than diffuse. Why do some speakers seem to tolerate being faced away better than others?
No, this isn't strictly true - at least not in recorded stereo as opposed to synthetic stereo from the studio. The point is that in recorded stereo the S channel needs boosting to compensate for the 6dB/octave dipole loss - so it is no longer "nearly mono". Any room modes in the listening space are linear and simply added to the signal in the recording, and so not relevant to this part of the discussion either.
!!!
Thank you.
And thanks to all the professionals who contribute here.
Listened in the afternoon the rehearsals of an acoustic trio, in a reflecting basement. No image, no fixed positions, each of them filled the wall and beyond.
In the night I met a guitarist posted in a portal of the '600 ... again no image, no fixed position, he also filled the tiny square.
For this kind of events I think that wide diffusion and reflective walls are good.
Correct, not true. I showed proof of that on this forum years ago, and Geddes accepted that proof. Old myths die hard.
However, stereo LF is thought not to matter because LF in small (domestic) listening rooms isn't directional due to modes and steady state bass build up. In my experience and tests, that isn't entirely true, either. LF can be directional even in modest size rooms. My testing also indicates that this may be listener specific - some people have a strong sense of LF location, other do not.
Bottom line: Does LF directionality matter to you? Does it add to your enjoyment? Different people have different answers.
Most commonly the term is related to the so-called Schroeder frequency.
This Schroeder frequency denotes the transistion from the frequency region where the room´s modal response dominates, to the frequency region where reflection and reverberation dominate.
So, if the Schroeder frequency is below the audio band then the room is definitively a "non small" room, which is typical for large venues like concert halls.
For normal room sizes the Schroeder frequency is more likely in the 200 - 300 Hz region.
As the reverberation time is part of the equation to calculate the Schroeder frequency it depends on the actual room construction/equipment, but from the mere dimensions your room qualifies for a acoustically small room.
Your welcome.
Although there is nothing ensured without measuring the properties of your room, at a first glance i´d say that the construction might lead to less severe problems in the modal region, because the drywood walls and ceiling along with the glass windows are less stiff in comparison to concrete or stone walls and will therefore probably already provide some attenuation for the standing waves.
Although there is nothing ensured without measuring the properties of your room, at a first glance i´d say that the construction might lead to less severe problems in the modal region, because the drywood walls and ceiling along with the glass windows are less stiff in comparison to concrete or stone walls and will therefore probably already provide some attenuation for the standing waves.
It is as hard to define the transition from modal to geometric acoustics in words as it is analytically. That's because we can see characteristics of both types of acoustics in this transition area. No room in a home is going to be geometric below 100-150 Hz, nor is it likely that we will see modal behavior above 200-250 Hz. The room that you mention is a little smaller than mine, mine is well sealed and heavily damped at LFs with dampened wall construction. It is modal below about 120 Hz, and clearly geometric above 200 Hz. Your room will probably have numbers higher than this.
Ok, but what do you mean by that?
I assume that it is sort of selfexplanatory to you, but unfortunately it isn´t for me ......
I was reading (and it somewhat agrees with my experience) that the voicing of loudspeakers by American companies mostly have higher low frequency output compared to European ones as drywall is more standard in the US than in Europe to compensate for higher losses at low frequencies. Drywall construction (especially single sheet) is more leaky largely below 100Hz.
Standing waves are part of low frequencies room acoustics and if the room modes are well spaced is attenuation something positive?
Regarding "spaciousness" and early reflections. Is it safe to assume that if the object that the sound is reflecting from is something very uniform, like a table, that it will have a bad effect on frequency response and sound bad?
But if the object is more random, like a pile of of rocks, the sound will reflect more randomly and be spacious. Also I imagine speakers with wider horizontal dispersion, especially arrays, would do this better.
But if the object is more random, like a pile of of rocks, the sound will reflect more randomly and be spacious. Also I imagine speakers with wider horizontal dispersion, especially arrays, would do this better.
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Room Acoustics
It seems that its the lateral reflections that we perceive as good and contribute to spaciousness. But obviously one wants to absorb if the off axis sound itself isn't good.
So "good" lateral reflections are the ones that might want to be diffused. Array type speakers excel at this.
Ethan Winer argues more for a dead room Early Reflections Are Not Beneficial
It seems that its the lateral reflections that we perceive as good and contribute to spaciousness. But obviously one wants to absorb if the off axis sound itself isn't good.
So "good" lateral reflections are the ones that might want to be diffused. Array type speakers excel at this.
Ethan Winer argues more for a dead room Early Reflections Are Not Beneficial
The logic flaw in Ethan Winters reasoning is that there is not 1 reflection, there are many.
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