wgb113
Active Member
Would it be wrong to simply suggest to the OP that it's a matter of preference when it comes to 1st reflections in their room as to whether the diffuse/absorb/do nothing?
It think that's valid. It highly depends on areas like:Would it be wrong to simply suggest to the OP that it's a matter of preference when it comes to 1st reflections in their room as to whether the diffuse/absorb/do nothing?
This is why we have targets of 0.2 to 0.5 for "RT60" for our listening spaces. If RT60 had no value, we could not make such suggestions.
My "pedantry" in the area is actually the belief the community of small room acoustics and was established decades ago.
This is an area I don't think short listening studies tell the whole truth by the way. What's most impressive right away isn't necessarily what's preferred over time in my experience. That's part of the reason I prefer studies on accuracy. "Preference" isn't very straightforward.
Would it be wrong to simply suggest to the OP that it's a matter of preference when it comes to 1st reflections in their room as to whether the diffuse/absorb/do nothing?
Is there any choice?Physics works. I say that for a reason.
Who does this kind of thing in small rooms? RT60 in all cases, good and bad, is used as a secondary or even tertiary metric. Primary metrics are frequency response, reflections (treat or not), etc. RT60, or frankly someone's ear, is used to determine if the room is too dead or too live. That's all.Small rooms that are treated according to RTx measurements end up most of the time becoming encredible poor and needs to be fixed later.
Only if you ignored other facts that you want such absorption to be broadband in which case 4 inch becomes minimum.If true reverberation time existed in small rooms, that would imply that thin absorption would work very well.
Is there any choice?
It's commonly done by those who believe RT60 exist in a small room. Typically large room acousician who don't understand small room acoustics is completely different and they wrongly use large room acoustics methods to small rooms. It happens often.Who does this kind of thing in small rooms? RT60 in all cases, good and bad, is used as a secondary or even tertiary metric. Primary metrics are frequency response, reflections (treat or not), etc. RT60, or frankly someone's ear, is used to determine if the room is too dead or too live. That's all.
I corrected you on this very thing three years ago: https://www.audiosciencereview.com/.../lets-discuss-room-correction.1448/post-38324Like pointed out in the link about small room: there is no Dc, no well mixed sound field, hence, no reverberation but merely a series of early reflected energy, the measurement of RT60 becomes meaningless in such environments.
In a large room with true reverberation you can rely on random incidence measurements of acoustic treatment. If true reverberation existed in small rooms, you could do the same there. But that's not the case. Absorbents function very differently in small rooms compared to large rooms. Something that we see when measuring the rooms as well. The reason is because reverberation time doesn't exist in small rooms.Only if you ignored other facts that you want such absorption to be broadband in which case 4 inch becomes minimum.
It is true that for a single number value, RT60 at 500 Hz is used by that is a convention and again part of a rough metric.
These rooms and those in which the recordings are reproduced are fundamentally different from live performance spaces, being smaller and acoustically far more absorbent—even large cinemas. When reverberation times measure around or below 0.5 s, one has to acknowledge that this is not reverberation in the original “diffuse field” sense; it is something else.
We continue to talk about reverberation times and invoke notions of critical distance, etc. The properties of acoustical materials are measured as if they were to be placed in diffuse sound fields: randomincidence absorption coefficient for example. These are mismatched concepts and this is where problems arise.
There's no misunderstanding here. Fundamental point: modal decay rates are not reverberation. Reverberation is “the time in seconds that it takes a diffuse sound field, well beyond a real critical distance, to lower in level by 60 dB when the sound source is silenced.” Modal decay rates are dB-per-second (dB/s) rate of decay for a specific modal frequency.
Who does this kind of thing in small rooms? RT60 in all cases, good and bad, is used as a secondary or even tertiary metric. Primary metrics are frequency response, reflections (treat or not), etc. RT60, or frankly someone's ear, is used to determine if the room is too dead or too live. That's all.
Absorbents function very differently in small rooms compared to large rooms. Something that we see when measuring the rooms as well.
Oh yes there is. You keep misunderstanding or ignoring the fact that multiple posters have specifically differentiated modal content. You seem to be under the impression that people are just taking a Rt single value at a spot frequency, or at modal frequencies and basing their treatments on this.
Amir has covered Dc.
Of course the frequency response of the room is the more important .
Firsts reflexions so gating : (2 ms/5ms/10ms/20ms/50ms/100ms)
For the RT 60 I prefer write "RT 60" even when used in smalls rooms, but I don't fight for that ! !
But for the quality of the sound of listening room I olso prefer "RT 60" of 0,2.
Notice what is important, especially in small rooms is the "RT 60" dont fall in treeble frequencies . Its gives bad and dead sound
A gather of data doesn't prove anything. You need to consider the conditions. From the paper you posted the graph:Here is another from AES/ASA paper measuring small rooms and their Dc:
As you see they all have critical distances despite the rooms being acoustically "small."
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They are overlooking the preconditions.The new method uses measurements made within the critical distance; it does not require that the reverberant energy be uniform in the room.