• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Perceptual Effects of Room Reflections

Blaspheme

Senior Member
Joined
Apr 14, 2021
Messages
461
Likes
515
Interesting. I'd never thought to see this in terms of cognitive styles. I have observed over the years that while most people perceive the same things, people differ in what they most value. Musical preferences matter here -- the criteria for studio rock are different than the criteria for acoustical music, say -- as does familiarity with live music (those who aren't familiar with live acoustical music prefer boosted highs, for example). That last I think is important. I can sit my late father's third wife down, for example, and play something, and she makes astute observations, despite the fact that she knows nothing about audio and isn't at all interested in it. That's because she regularly attends concerts and knows what they sound like.
Yes, I'm thinking it may influence what we enjoy, value and notice. We are listening to the same signal (more or less as equipment and room allows) but will recall different aspects because of this. And often refocus when listening to the same material again. I'm not too surprised that a concert-goer may discuss sound in an analytical way, assuming they are that way inclined at all (to analyse a performance and their experience of it).
 

Blaspheme

Senior Member
Joined
Apr 14, 2021
Messages
461
Likes
515
...beyond science and the above classification, as s.o. who generally likes to get a glimpse on" the ghost in the machine" I think I also need to understand what´s going on on-stage when listening to music. Maybe this sets (or maybe also limits) my preference mainly to chamber type of music where I am personally able to follow the musicians in their play. I can enjoy live music best from both the acoustical and visual side in parallel. At home I need to "rebuild" the missing visual picture as if I had my eyes closed in a life presentation. Presumably this is why I prefer this kind of studio monitoring approach with best possible spatial resolution and accept less immersive sound (still being able to acknowledge immersive sound when listening in cathedrals, to large orchestras or rock/pop/electronic music just because of the associated perception). On the other hand I was astonished to experience how effect-rich music e.g. by Yello (specificly older productions) yields a very intense physical impression in such a listening environment, just because of its highly dynamic content, which is probably not so much limited or cut down by superposition of a higher amount of reflections...
I'm quite partial to very abstract electronic pieces (think Autechre or Ryoji Ikeda) with no acoustic component in the instrumentation and very little human expressive element. Naturalistic because it can be something like walking through a landscape, or sitting on a cliff as a storm approaches or abates. Or the furious chatter of flocks of birds, etc. Well, I hope it's spatial and naturalistic intelligence and not sociopathy.

As you mentioned it, I'm more rarely taken by thought of where the performers are positioned or what they are up to. But I wonder if you have stronger interpersonal intelligence also, vis-à-vis the performers, or if the desire to re-construct is basically visual-spatial. I do think that basing reproduction on live acoustic performance at least gives you a tangible reference—somewhat elusive for studio-assembled sound, especially abstract pieces—which is both easier to approach but likely harder to perfect. The conventional live music I go to depends on PA for sound, there are no natural instrument locations. The more esoteric spatial pieces may well have custom audio setups that certainly could be recorded as such, but rarely would be. That said, studio assembly often creates a soundscape for stereo, which may be simple or complex, with many examples of the latter these days.

So imaging specificity and soundscape dimensions are system and setup factors for me. I've gone for the fairly directional speaker style, toe-in to face the listening position at least, along with some DSP. The latter full range which improved imaging noticeably. Room treatment of both floor and (raked) ceiling. I've yet to try specific side treatment (apart from sliding the walls open) but lateral extension of the soundscape is present, at least where the recording has it rather than totally due to reflections (I surmise, not certain).


Edit: my temporary listening space is a mezzanine loft half-length, so space is tight—I'm sitting mid-room—and speakers are necessarily close to the front wall. A rough model shows same side reflection 3.2 ms behind direct, within the 1-5 ms window for precedence effect:

Screen Shot 2021-07-06 at 2.58.06 pm.png


The opposite side reflection is 9.4 ms late, and the double bounce is roughly twice that:

Screen Shot 2021-07-06 at 3.02.51 pm.png


Screen Shot 2021-07-06 at 3.12.05 pm.png


The longer times are more problematic. More directional speakers will mitigate this. As will side wall absorption and/or diffusion: I suspect the benefit of either/both isn't so much for the initial same-side reflection, but the later-arriving cross and bounce, wrt imaging.
 
Last edited:

eliash

Senior Member
Joined
May 29, 2019
Messages
407
Likes
209
Location
Bavaria, near lake Ammersee
I'm quite partial to very abstract electronic pieces (think Autechre or Ryoji Ikeda) with no acoustic component in the instrumentation and very little human expressive element. Naturalistic because it can be something like walking through a landscape, or sitting on a cliff as a storm approaches or abates. Or the furious chatter of flocks of birds, etc. Well, I hope it's spatial and naturalistic intelligence and not sociopathy.

As you mentioned it, I'm more rarely taken by thought of where the performers are positioned or what they are up to. But I wonder if you have stronger interpersonal intelligence also, vis-à-vis the performers, or if the desire to re-construct is basically visual-spatial. I do think that basing reproduction on live acoustic performance at least gives you a tangible reference—somewhat elusive for studio-assembled sound, especially abstract pieces—which is both easier to approach but likely harder to perfect. The conventional live music I go to depends on PA for sound, there are no natural instrument locations. The more esoteric spatial pieces may well have custom audio setups that certainly could be recorded as such, but rarely would be. That said, studio assembly often creates a soundscape for stereo, which may be simple or complex, with many examples of the latter these days.

So imaging specificity and soundscape dimensions are system and setup factors for me. I've gone for the fairly directional speaker style, toe-in to face the listening position at least, along with some DSP. The latter full range which improved imaging noticeably. Room treatment of both floor and (raked) ceiling. I've yet to try specific side treatment (apart from sliding the walls open) but lateral extension of the soundscape is present, at least where the recording has it rather than totally due to reflections (I surmise, not certain).


Edit: my temporary listening space is a mezzanine loft half-length, so space is tight—I'm sitting mid-room—and speakers are necessarily close to the front wall. A rough model shows same side reflection 3.2 ms behind direct, within the 1-5 ms window for precedence effect:

View attachment 139401

The opposite side reflection is 9.4 ms late, and the double bounce is roughly twice that:

View attachment 139402

View attachment 139404

The longer times are more problematic. More directional speakers will mitigate this. As will side wall absorption and/or diffusion: I suspect the benefit of either/both isn't so much for the initial same-side reflection, but the later-arriving cross and bounce, wrt imaging.

Not having elaborated my listening room that much toolwise (very impressive, which tool is it?), I assume direct reflections (from walls close to the speaker) are more relevant for audible distortion perception (like roughness or harshness impression) and opposite wall reflections (from opposite walls related to the speaker) may be more relevant for "out-of-stereo-width" perception. Regarding these personally perceived distortions, the tilted ceiling under which the speakers are located were actually severe contributors to that effect. I started treating the side walls with absorbers first and did not realise at once that the tilted ceiling is much closer as a source of early reflection (delay ~1m). The initial side wall treatment already yielded a much more stable mono image, but the absorbers (only 60x60cm) mounted to the tilted ceiling brought the "breakthrough" in terms of endurable distortion reduction...
 
Last edited:

Blaspheme

Senior Member
Joined
Apr 14, 2021
Messages
461
Likes
515
Not having elaborated my listening room that much toolwise (very impressive, which tool is it?), I assume direct reflections (from walls close to the speaker) are more relevant for audible distortion perception (like roughness or harshness impression) and opposite wall reflections (from opposite walls related to the speaker) may be more relevant for "out-of-stereo-width" perception. Regarding these personally perceived distortions, the tilted ceiling under which the speakers are located where actually severe contributors to that effect. I started treating the side walls with absorbers first and did not realise at once that the tilted ceiling is much closer as a source of early reflection (delay ~1m). The initial side wall treatment already yielded a much more stable mono image, but the absorbers (only 60x60cm) mounted to the tilted ceiling brought the "breakthrough" in terms of endurable distortion reduction...
Amcoustics added a ray tracing tool a little while back. It's basic but useful. My loft ceiling also slopes and starts quite close to the speakers, I did a vertical section originally but neglected to save it, should try again. Interesting—and not surprising after thinking about it—that your treatment there helped.
 
Last edited:

josh358

Senior Member
Joined
Jun 13, 2017
Messages
493
Likes
387
I used a poor example of what Griesinger had in mind, drawing on my faulty memory. So let me quote him:

"As the quartet plays tirelessly on stage we walk backward away from them into the hall... At first it is easy to localize each instrument, and tell which played each note. The sound has an exciting, attention-grabbing quality. As you walk back the sound remains close and exciting. But suddenly in distance range of one or two rows all the instruments blend together into a fuzzy ball of sound. The attention-grabbing effect is gone. We call the distance at which this happens the Limit of Localization Distance, or LLD." (From this paper, second page.)

He reports good localization at Row X, near the center, in Boston Symphony Hall.

An interesting experiment. I wonder if it's dependent on the specific hall.

I have not been aware of the "double image" you describe from a setup which minimizes the early reflections while cultivating later ones (later than 10 milliseconds). Reports I get indicate the spatial presentation changes significantly from one recording to the next, which implies that the recordings' varying spatial cues (rather than the playback room's consistent spatial cues) are dominating perception. Imo this would indicate these later-arriving reflections are indeed acting as effective "carriers" of the venue cues on the recording, probably primarily the reverberation tails. See the last four paragraphs of this post for an example.
You shouldn't heart the double image if you minimize early reflections and cultivate later ones. That's been my point throughout this thread -- sorry if I wasn't clear. The problem is that the ITDG of the room interferes with the ITDG on the recording. The recording's ITDG still affects spatial presentation, though. In my experience, the effect can be heard by moving the speaker progressively away from reflective room services. The apparent size of the venue increases, and imaging becomes progressively more holographic, for want of a better term. This is without room treatment -- diffusion or absorption change the presentation, although in my experience, don't quite match the effect of moving the loudspeakers away from the walls.

Under what should have been very poor conditions - a small untreated hotel room at Axpona - one listener challenged my schpiel by asking us to play a recording he brought which was made in a concert hall he was familiar with. He later posted this on another forum:

"The recording was a FLAC rip of the CD layer of an RCO Live SACD: Shostakovich—Symphony No. 15; Concertgebouw Orchestra/Bernard Haitink conductor. It's a live recording from March of 2010 (Haitink made a much earlier recording of the same piece with the London Philharmonic; he was the first person to record all the Shostakovich symphonies.) For a couple of years, this has been my go-to symphonic recording when I have just a short time to get a sense of an unfamiliar system. It's an excellent performance, something I can listen to repeatedly without going nuts, which is important at a show. In terms of audiophilia, it's an extremely detailed yet atmospheric representation of an orchestra, with excellent dynamics and fully characterized instrumental colors (bells, solo turns by violin, flute, piccolo, string bass, trumpet, etc.) And—with the right audio gear—it successfully renders the essence of (IMO) one of the greatest 3 or 4 concert halls on earth, the Concertgebouw (thus the orchestra's name) in Amsterdam. I've heard music there, and there's truly a sense of sound being present in the air around you.

"The multichannel program on the RCO Live SACDs (there are dozens) get this last aspect right; so did the Bienville Suite, nearly to the same degree, despite the presence of only two channels. My concern when Duke told me about the rear-firing drivers was that this would impart some generic, Bose-like spaciousness to the recording, but that wasn't the case—what I heard was the unique acoustic signature of the Concertgebouw." [emphasis Duke's]

Here is the room, for context. The quasi-triangular speakers have rear-firing drivers whose responses were tailored to their task. You can also see two of the four small subs we used, peeking out from behind the main speakers. Photo by Scott Hull of Part-Time Audiophile.

View attachment 139321
Interesting -- I missed your room last time around, will make sure to drop in this time.
 

Duke

Major Contributor
Audio Company
Forum Donor
Joined
Apr 22, 2016
Messages
1,523
Likes
3,745
Location
Princeton, Texas
Thank for your reply Josh, and I should have known better than to misunderstand you.

The problem is that the ITDG of the room interferes with the ITDG on the recording. The recording's ITDG still affects spatial presentation, though. In my experience, the effect can be heard by moving the speaker progressively away from reflective room services. The apparent size of the venue increases, and imaging becomes progressively more holographic, for want of a better term.

I don't think we can make the room's Initial Time Delay Gap, ITDG, long enough for it not to compete with the ITDG on the recording, but making it as long as we reasonably can, as you describe, seems to be beneficial.

This is why I suspect that it is the reverberation tails on the recording (which are delivered primarily by the in-room reflections) which are largely responsible in playback system setups where the venue cues dominate the spatial impression.

Incidentally, a usefully longer ITDG is one of the advantages of a dipole (and some other types of polydirectionals): With dipoles the ITDG - the time gap between the direct sound and the first strong reflection - is the time it takes for the backwave to arrive, rather than the time it takes for sidewall reflections to arrive, the latter being the case with conventional speakers in the absence of really good room acoustics.
 
Last edited:

josh358

Senior Member
Joined
Jun 13, 2017
Messages
493
Likes
387
Thank for your reply Josh, and I should have known better than to misunderstand you.



I don't think we can make the room's Initial Time Delay Gap, ITDG, long enough for it not to compete with the ITDG on the recording, but making it as long as we reasonably can, as you describe, seems to be beneficial.

This is why I suspect that it is the reverberation tails on the recording (which are delivered primarily by the in-room reflections) which are largely responsible in playback system setups where the venue cues dominate the spatial impression.

Incidentally, a usefully longer ITDG is one of the advantages of a dipole (and some other types of polydirectionals): With dipoles the ITDG - the time gap between the direct sound and the first strong reflection - is the time it takes for the backwave to arrive, rather than the time it takes for sidewall reflections to arrive, the latter being the case with conventional speakers in the absence of really good room acoustics.
Good point. My own speakers are dipoles, about 5' out from the front wall, and since they're toed in the first reflection from the front wall is somewhat attenuated by the dipole pattern -- more comes from the corners, which means an even longer path. The dipole null also suppresses the reflection from the proximate sidewall, so what comes from the side is from the opposite wall and delayed as well. Finally, I've discovered, as have others, that diffusion works quite well in the front *corners* of the room, where most of the backwave energy is directed.
 

Trdat

Addicted to Fun and Learning
Forum Donor
Joined
Sep 6, 2019
Messages
967
Likes
396
Location
Yerevan "Sydney Born"
Ha! Rolling his eyes more likely.

We conducted controlled blind in-house testing wherein we allowed listeners to dial in (from the listening chair) their preferred amount of relatively late-onset reverberant energy to add to our controlled-pattern main speakers, and arrived at very different conclusions from what Amar Bose was doing. We found a MUCH HIGHER direct-to-reverberant ratio to be preferred.

By way of illustration, if you imagine starting out with the 120-degree-horizontal radiation pattern of the JBL M2, what we found was that sending about 70 degrees towards the listening area and about 50 degrees elsewhere would be about the right balance. So in effect we have roughly the same direct-to-reverberant sound ratio as the M2, but the temporal "center of gravity" of our reverberant sound is pushed back in time in a normal room, and is closer to what might be found in a room with a deliberate early-reflection-free zone.

Anyway, stop me if you've heard this one:

Paul Klipsch was strolling down the sidewalk when who does he see coming towards him but Peter Walker, Henry Kloss, and Amar Bose. So Paul cups his hands around his mouth, horn-like of course, and calls out, "Hello gentlemen! How are you doing?" Well, Peter Walker is ecstatic; Henry Kloss is infinitely baffled; and Amar Bose turns around to face the opposite direction and says, "Fine, Paul! And how are you?"

70 degrees from one side I am presuming? Meaning the listening position will be slighlty off centre axis with 50 degrees pointing away to a wall to extract late onset reflections back to the listening position...?

This is interesting as lately I have been influenced with the pro reflection and envelopment theories(Griesenger) and it seems some comments about how the ear brain connections adapts must be true as you end up enjoying whatever room after you have somewhat adapted but switching back and forth I feel reflections do add something, I have left my lateral reflections untreated(although with the horns pointing away from listening position I have no early side wall reflections). Plus, I am in the direct field due to the my tiny room.

More to the point, when you say late onset reverberant energy are we talking about general decay, high frequency reflections, low frequency envelopment or all of the above?
 

Duke

Major Contributor
Audio Company
Forum Donor
Joined
Apr 22, 2016
Messages
1,523
Likes
3,745
Location
Princeton, Texas
70 degrees from one side I am presuming? Meaning the listening position will be slighlty off centre axis with 50 degrees pointing away to a wall to extract late onset reflections back to the listening position...?

Actually I was thinking of about 70 degrees forward-firing, and then about 50 degrees rear-firing, then setting the speakers up with a LOT of toe-in (axes criss-crossing in front of the sweet spot), which correspondingly toes-out the rear-firing elements.

More to the point, when you say late onset reverberant energy are we talking about general decay, high frequency reflections, low frequency envelopment or all of the above?

I was talking about reflections which arrive late enough to not degrade the first-arrival sound, which primarily applies to the shorter wavelengths in home audio . To a ballpark first approximation, I take this to be about 10 milliseconds in a home audio setting (and how loud the reflections are can also come into play). Quoting Griesinger:

"Transients are not corrupted by reflections if the room is large enough - and 10ms of reflections free time is enough."

Geddes says this 10 milliseconds will allow the ear to differentiate the direct from the reflected sound down to 700 Hz, and IIRC he quotes Griesinger as saying that most of the information in sounds lies between 700 Hz and 7 kHz, so 10 milliseconds is arguably a worthwhile target.

I try to meet this 10 milliseconds target by criss-crossing my relatively narrow-pattern front-firing arrays to mitigate the early same-side-wall reflection, then have a long enough reflection path for my rear-firing energy to arrive after 10 milliseconds or so.
 
Last edited:

Trdat

Addicted to Fun and Learning
Forum Donor
Joined
Sep 6, 2019
Messages
967
Likes
396
Location
Yerevan "Sydney Born"
Actually I was thinking of about 70 degrees forward-firing, and then about 50 degrees rear-firing, then setting the speakers up with a LOT of toe-in (axes criss-crossing in front of the sweet spot), which correspondingly toes-out the rear-firing elements.
I'm going to be honest and say I am a little confused, when you say rear firing are you talking about the omnidirectional part of the bass frequencies or a speaker type that radiates soundwaves to the rear?

I criss cross my toe in axis(horn speakers) like you mention and aim to get a reflection from the opposite side wall coming back to the listening position after about 10ms, haven't measured yet and not versed to figure out which reflection is from where on REW but I know its possible to extract from a impulse response. This is Geddes approach for narrow directivity speakers and from my measurements there is an improvement in the way the impulse repsonse decays with no strong early reflections but I am not an expert.

I was talking about reflections which arrive late enough to not degrade the first-arrival sound, which primarily applies to the shorter wavelengths in home audio . To a ballpark first approximation, I take this to be about 10 milliseconds in a home audio setting (and how loud the reflections are can also come into play). Quoting Griesinger:
This is great info, happy to see that there is some kind of consensus on what constitutes as those degrading reflections with some evidence from both Griesenger and Geddes. Griesenger's literature is difficult to untangle at times.

I read an article can't remember by who, possibly Floyd Toole or Griesenger in which the article states that early reflections are beneficial for small rooms especially lateral reflection but the author goes onto differentiating between early reflections and early early reflections and states that early early reflections degrade first arrival sound which are before approx 6ms.

On a side note, and absolutely not advising anyone to do this but thought ill mention it to see others reactions, my wide dispersion speakers(my secondary speakers) are placed inbetween the side wall and large 120 litre speaker boxes(which are my main speakers in the middle of the room) firstly because they are used at times as front surrounds also because I have no other space but I have toed them in such way that I get reflections off the large cabinet back to the side wall and then back to the listening position. And the other side(of the speaker) toed out away from the wall enough to reduce reflections.

My only problem is I dont know much about the off axis spectral content of the wide dispersion speakers which is very important in this situations.

PXL_20211018_143150376.jpg
 

Duke

Major Contributor
Audio Company
Forum Donor
Joined
Apr 22, 2016
Messages
1,523
Likes
3,745
Location
Princeton, Texas
I'm going to be honest and say I am a little confused, when you say rear firing are you talking about the omnidirectional part of the bass frequencies or a speaker type that radiates soundwaves to the rear?

I think the general idea can be implemented in different ways, but I use a dedicated rear-firing driver. Here are photos of the front and back of one such design:

7-595.jpg


13-605.jpg


I read an article can't remember by who, possibly Floyd Toole or Griesenger in which the article states that early reflections are beneficial for small rooms especially lateral reflection but the author goes onto differentiating between early reflections and early early reflections and states that early early reflections degrade first arrival sound which are before approx 6ms.

I think Siegfried Linkwitz used 6 milliseconds as his target, could it have been something he wrote? Ime 10 milliseconds is a definite improvement, based on sighted listening tests with fullrange dipole speakers (SoundLabs) at different distances from the wall behind them. I arrived at the 10 millisecond threshold by ear before encountering "confirmation" from Geddes and later Griesinger.
 

MaxRockbin

Active Member
Joined
May 26, 2021
Messages
109
Likes
131
Location
Portland, Oregon

As an example, at 300 Hz source frequency (horizontal axis), the ear’s sensitivity or discrimination is a narrow 60 Hz (vertical axis). At the other extreme, for a source frequency of 10 KHz, the level climbs way up to 1.1 KHz. This readily shows that we are far less sensitive to frequency variations at 10 KHz than we are at 300 Hz.
Could someone help me understand this in the original post?

This seems to say that, per the example, we really can't tell 300hz from 300hz +/- 30hz (so a 60hz window). But if you try out a frequency generator like this one it seems like it's not even close. It's very easy to hear 300 vs 310, say.
Or (just eyeballing the graph), something like 1200hz +/- 60hz? Toggling between 1200/1250 seems completely obvious.

So what am I missing? My hearing isn't exceptional and I'm playing at a reasonable volume and my room/speakers are reasonably flat with those variation (more so in the upper range, but the difference is even more apparent there)?

Thanks!
 

Trdat

Addicted to Fun and Learning
Forum Donor
Joined
Sep 6, 2019
Messages
967
Likes
396
Location
Yerevan "Sydney Born"
I think the general idea can be implemented in different ways, but I use a dedicated rear-firing driver. Here are photos of the front and back of one such design:
Never came across a speaker like that in my lifetime in audio very fascinating. Is that a type of speaker you have at home? When you mention seperate driver radiating to the rear is it within the cabinet or just a horn pointing to the back wall?

So back radiating will provide significant envelopment and more reflections, from the back wall to the side and from there to the listening position after about 10-15 ms with decent spectral content thanks to the wide horizontal dispersion pattern.

Yes, your correct Linkwits mentions 6ms but it was a short article written somewhere else can't remember.

And lastly do you have any more information about the blind tests you performed?
 

dasdoing

Major Contributor
Joined
May 20, 2020
Messages
4,209
Likes
2,675
Location
Salvador-Bahia-Brasil
Could someone help me understand this in the original post?

This seems to say that, per the example, we really can't tell 300hz from 300hz +/- 30hz (so a 60hz window). But if you try out a frequency generator like this one it seems like it's not even close. It's very easy to hear 300 vs 310, say.
Or (just eyeballing the graph), something like 1200hz +/- 60hz? Toggling between 1200/1250 seems completely obvious.

So what am I missing? My hearing isn't exceptional and I'm playing at a reasonable volume and my room/speakers are reasonably flat with those variation (more so in the upper range, but the difference is even more apparent there)?

Thanks!

imo this is an audiophile misconception.
it's about masking. it is true for a white noise, not for single notes
 

Duke

Major Contributor
Audio Company
Forum Donor
Joined
Apr 22, 2016
Messages
1,523
Likes
3,745
Location
Princeton, Texas
Never came across a speaker like that in my lifetime in audio very fascinating. Is that a type of speaker you have at home?

Ha! I'll have to fire my marketing department. Oh wait... that's me.

That's one of my products. I have that type of speaker at home, but not that particular model (which is called the "Azel Tower").

When you mention seperate driver radiating to the rear is it within the cabinet or just a horn pointing to the back wall?

In the speaker in the photo, it's just the horn. I've done others, some with coaxials and some with arrays.

And lastly do you have any more information about the blind tests you performed?

The idea was not to gather data sufficient to prove anything to anyone on an online forum... the idea was just to gather data sufficient to inform a few product development decisions.

The front-firing drivers were driven by one amplifier, and the rear-firing drivers were driven by a separate amplifier that had a remote volume control. The listener adjusted the loudness of the rear-firing drivers with the remote control, and nobody was looking at the readout on the remote. If the rear-firing drivers are too loud, clarity starts to be degraded. Anyway in one instance both listeners (yeah the sample size was too small) set the level of the rear-firing drivers at 13 dB below the level of the front-firing array, as measured at the listening position using pink noise. In another instance (different speakers, different room) both listeners arrived at a setting of 11 dB below the level of the front-firing drivers (or so I was told - I was not present).
 
Last edited:

MaxRockbin

Active Member
Joined
May 26, 2021
Messages
109
Likes
131
Location
Portland, Oregon
imo this is an audiophile misconception.
it's about masking. it is true for a white noise, not for single notes
You probably mean that if someone played white noise over some range of frequencies containing the critical band around some frequency, like 300hz +/- 30 in the example in the post, a person could not tell the difference in sound if you subtracted some interval smaller than the critical band from it. The reply was pretty succinct, so I wasn't sure if that's the point you meant to clarify.

If my question was about an "audiophile" misconception, or any other kind, those are things knowledgeable people on the forum might illuminate. Which is why I asked.
 

dasdoing

Major Contributor
Joined
May 20, 2020
Messages
4,209
Likes
2,675
Location
Salvador-Bahia-Brasil
You probably mean that if someone played white noise over some range of frequencies containing the critical band around some frequency, like 300hz +/- 30 in the example in the post, a person could not tell the difference in sound if you subtracted some interval smaller than the critical band from it. The reply was pretty succinct, so I wasn't sure if that's the point you meant to clarify.

If my question was about an "audiophile" misconception, or any other kind, those are things knowledgeable people on the forum might illuminate. Which is why I asked.

I don't realy fully understand the concept,
but it basicly means that dips inside those bands are masked by other frequencies afaiui.
what I am saying is that if you have a single note in that dip, it will be atenuated; so the concept has to be taken with a grain of salt for music
 

josh358

Senior Member
Joined
Jun 13, 2017
Messages
493
Likes
387
I don't realy fully understand the concept,
but it basicly means that dips inside those bands are masked by other frequencies afaiui.
what I am saying is that if you have a single note in that dip, it will be atenuated; so the concept has to be taken with a grain of salt for music
Interesting question, isn't it? The brain is pretty good at filling in dips above the Schroeder Frequency (and to some extent, even below). It has to be, because room reflections cause all kinds of comb filtering. It's known that peaks are more audible than dips, and high Q filters more than low Q ones. But I don't know how deeply your question has been studied. If anyone does, I'd be curious to know.
 

DonH56

Master Contributor
Technical Expert
Forum Donor
Joined
Mar 15, 2016
Messages
7,835
Likes
16,497
Location
Monument, CO
Interesting question, isn't it? The brain is pretty good at filling in dips above the Schroeder Frequency (and to some extent, even below). It has to be, because room reflections cause all kinds of comb filtering. It's known that peaks are more audible than dips, and high Q filters more than low Q ones. But I don't know how deeply your question has been studied. If anyone does, I'd be curious to know.
I thought low-Q (broader-bandwidth) frequency aberrations were more audible, rather than high-Q (narrowband)? For filters, high-Q filters may have more ringing, so maybe that is what you mean?
 

josh358

Senior Member
Joined
Jun 13, 2017
Messages
493
Likes
387
I thought low-Q (broader-bandwidth) frequency aberrations were more audible, rather than high-Q (narrowband)? For filters, high-Q filters may have more ringing, so maybe that is what you mean?
It's entirely possible that I've become so senile that I remember it backwards. :)
 
Top Bottom