1DDefine what you call a 1D and 2D diffuser, please.
2D
Obviously both are 3D
1DDefine what you call a 1D and 2D diffuser, please.
As you saidObviously both are 3D
I think of it the same way, because that literally makes sense, but I know GIK calls them 1D/2D if you look under pattern on their product page.I can only see the possibility of a 2D or a 3D diffuser. A 1D diffuser is just a plain wall! Or am I diffused by things at the moment?
@DjBonoBobo I am not an acoustician, but I do like to read. Since I lack personal experience, I will try to avoid unsupported assertions but instead provide references whenever possible. I think that your frustration comes down to both fundamental problems in how measurements are done and interpreted, as well as a failure in most discussions to simply identify individual preferences as the starting point for further exploration (e.g. https://www.audiosciencereview.com/...-of-lokki-bech-toole-et-al.27540/#post-950580). In a similar manner of different concertgoers having different preferences (clarity vs loud, reverberant sound vs timbre) and therefore arguing about what makes an optimal concert hall (or to make it a bit more complicated, whether LOC to improve the experience of more of the audience, like http://www.davidgriesinger.com/The_Physics_of_auditory_proximity_2.pptx), the discussion of what to do with reflections gets bogged down quickly without identifying or prioritizing preferences first.I have no technical expertise myself and get irritated quickly. On the one hand, I've been dealing with the optimization of my room for a long time (two examples of my "quest" for better room acoustics: 1 and 2), but I'm increasingly frustrated that I can't find any consistent guides.
As far as I know, there are no reliable measurements or tests anywhere on room acoustic measures, and if you buy something yourself, you actually have to decide beforehand and only know at the very end - after you have spent hundreds or thousands and assembled everything, whether the effect has occurred as desired.
Even if you hire a professional, you don't know what you're going to get - at least I've heard various rather dissatisfied testimonials. You certainly can't generalize all that, but it seems to me to be very difficult to really get a good picture yourself of what measures are really useful and which are not.
The discussion of what to do with reflections from the side walls alone is already completely opaque, since there are renowned experts for all variants who argue convincingly in favor of one or the other measure (diffuse, absorb, reflect).
My state of knowledge so far was that especially in small rooms absorbers should be preferred (as broadband as possible) and diffusers do not work or are even harmful. You now write the opposite.
As I said, I know nothing better but certainly much worse than you. But you make it sound as if the use of diffusers in small rooms is relatively clear and unambiguous - is that so?
You are very welcome. I’m happy that I made a small difference in your music enjoyment.I really have to thank you @sarumbear for opening this thread!
Diffusers need distance between them and the source or the listener. Possibly that’s why they didn’t work for you as the distance is very small.I have now discovered that GIK diffusors over my desk makes a dramatic improvement in sound quality in my office. It never really occurred to me to try and test them up there. I also tested the GIK diffusors on my front wall, but actually prefer the absorption that I currently have.
Do you mean like this? https://www.primacoustic.com/flexifuser/3D art as diffusers. Your second post got me wondering how hard it would be to have the blocks actuated to dial in a specific response. Some day I suppose. Does anybody offer an absorbent panel with adjustable wood slats mounted in front (like vertical blinds) yet?
I think you're describing something along the lines of difference between an RPG Skyline diffuser (https://www.rpgacoustic.com/skyline/) and a Vicoustic Multifuser DC3 (https://vicoustic.com/product/multifuser-dc3?multifuser-dc2-finishes=Black). From what I understand from Cox and d'Antonio, as well as Toole, the relative depths of the diffusers should determine the lower range of the effective frequency of diffusion. Angling likely helps with very small wavelengths, but when you look at the difference of depth related to the angle, as well as the size of the individual units, the wavelengths involved are likely above 10 kHz. Consider, by contrast, the effects of hearing damage related to age and concert attendance.Well, OK then, based on what the physics profs have taught me about wave propagation, the angle of reflection is equal to the angle of incidence, wrt a normal line perpendicular to the reflective surface. If the object is to break up the wavefront into smaller bits and send them off in different directions in order to reduce their perceivability (did I just make up a word?) at the listener’s ear, then perhaps what I wrote previously would hold. Or perhaps not. I hear you saying not necessarily,, read the papers, so I suppose the answer is in there.
Perhaps consider diffusers as acting directionally in terms of amplitude and phase, otherwise as scattering in different planes. If an appropriate sound wave hits a vertically oriented so-called 1D diffuser, it gets scattered in the horizontal plane (side-to-side, instead of just bouncing off like a beam of light hitting a mirror in a specular fashion). The horizontal plane is one dimension. If an appropriate sound waves hits a so-called 2D diffuser, it gets scattered in both the horizontal and vertical planes, which represents two dimensions. A 3D diffuser would have to scatter both in front and behind it, i.e. depth.I can only see the possibility of a 2D or a 3D diffuser. A 1D diffuser is just a plain wall! Or am I diffused by things at the moment?
I can't speak for @Hipper, but a few possibilities could include comb filter effects related to phase, as well as localization depending on placement of the diffusers:Can you explain what you meant by "I could hear them". What was it that you are hearing compared to the bare wall?
@DjBonoBobo Actually, Cox and d'Antonio also discuss cases of music practice rooms: "The experiments verified that by utilizing limited diffsorption, hemispherical ceiling diffusion and lateral wall diffusion, along with modal absorption, a very functional and enjoyable practice room could be attained."@DjBonoBobo I am not an acoustician, but I do like to read. Since I lack personal experience, I will try to avoid unsupported assertions but instead provide references whenever possible. I think that your frustration comes down to both fundamental problems in how measurements are done and interpreted, as well as a failure in most discussions to simply identify individual preferences as the starting point for further exploration (e.g. https://www.audiosciencereview.com/...-of-lokki-bech-toole-et-al.27540/#post-950580). In a similar manner of different concertgoers having different preferences (clarity vs loud, reverberant sound vs timbre) and therefore arguing about what makes an optimal concert hall (or to make it a bit more complicated, whether LOC to improve the experience of more of the audience, like http://www.davidgriesinger.com/The_Physics_of_auditory_proximity_2.pptx), the discussion of what to do with reflections gets bogged down quickly without identifying or prioritizing preferences first.
Regarding measurements, at least in terms of absorption, you might be interested to read https://www.stereophile.com/content/nwaa-labs-measurement-beyond-atomic-level and http://nwaalabs.ipower.com/Files/NWAA Labs/AES PNW Old Problems, New Solutions, Architectural Acoustics in Flux2.ZIP, as well as Toole's second edition of Sound Reproduction regarding angles of incidence and fabric coverings. For diffusion, see the Stereophile artcle above and http://nwaalabs.ipower.com/Files/NWAA Labs/Diffusion, When phase and energy becomes more important than directivity in the perception of space 2017 NOLA.pdf. Compare what he says about binary amplitude diffusion devices in the latter with comments regarding localization in the former vs perception of the room opening up in the latter, for example, but also what he implies about QRD devices in the former.
In terms of small rooms, Cox and d'Antonio (founder of RPG) write in their book "Acoustic Absorbers and Diffusers," "How far away should a listener be positioned from the diffusers? The distance from listener to diffuser can be determined by considering the scattered and total field. First consider the scattered field, i.e. just the reflections from the diffuser. A diffuser requires a certain time or distance to form a wavefront. There is an analogy to loudspeakers that can be made here. A listener would not consider sitting 30 cm from a multi-way loudspeaker, because the listener would be in the near field of one of the drivers. At some distance from the loudspeaker, all individual high, mid- and low frequency waves from the individual drivers will combine to form a coherent wavefront. The same holds true for scattering surfaces. They also can be thought of in terms of near and far field, although the situation is a bit more complex than for loudspeakers...Consequently, listeners should be positioned as far from scattering surfaces as possible. Precedence has shown that it is best if the listener is at least three wavelengths away from diffusers. Since diffusers used in listening room applications have a lower frequency limit of roughly 300–500 Hz, this means a minimum distance of 3m is recommended."
Also with "Acoustics of Small Rooms," Kleiner and Tichy distinguish between small rooms used for music reproduction and small rooms used for voice and music practice with interesting distinctions in discussion. They discuss the use of diffusion more in the latter than the former.
Anyway, just my thoughts reading your post. I think it may be a bit more complicated than what I'm interpreting from @sarumbear.
Young-Ho
Interesting...
I have no technical expertise myself and get irritated quickly. On the one hand, I've been dealing with the optimization of my room for a long time (two examples of my "quest" for better room acoustics: 1 and 2), but I'm increasingly frustrated that I can't find any consistent guides.
As far as I know, there are no reliable measurements or tests anywhere on room acoustic measures, and if you buy something yourself, you actually have to decide beforehand and only know at the very end - after you have spent hundreds or thousands and assembled everything, whether the effect has occurred as desired.
Even if you hire a professional, you don't know what you're going to get - at least I've heard various rather dissatisfied testimonials. You certainly can't generalize all that, but it seems to me to be very difficult to really get a good picture yourself of what measures are really useful and which are not.
The discussion of what to do with reflections from the side walls alone is already completely opaque, since there are renowned experts for all variants who argue convincingly in favor of one or the other measure (diffuse, absorb, reflect).
My state of knowledge so far was that especially in small rooms absorbers should be preferred (as broadband as possible) and diffusers do not work or are even harmful. You now write the opposite.
As I said, I know nothing better but certainly much worse than you. But you make it sound as if the use of diffusers in small rooms is relatively clear and unambiguous - is that so?
I used 3' x 6' absorption panels behind my head in a 24' x 14' x 9 ' rectangular room with large archways at each end of the room and the speakers along the long wall and it sounded fantastic. Then a peep here at ASR used diffusers behind his head and said the room sucked with them there so he put them on the front wall. I think for acoustician laymen such as ourselves your approach of adding a panel or two at a time is a good approach.or to the wall behind my listening position.
Though placement and spacing do matter, central > peripheral, also multiple smaller pieces > single larger one, as per Toole (in Sound Reproduction) and Sauro as previously linkedIt's pretty easy, just use mathematics and you know how much coverage is needed for every wall and ceiling when it comes to absorbing material and diffusion material. But just think of it as a "rule of thumb", measure, and re-measure step by step to know if you are moving in the right direction. The goal is to have an even reverberation time over the full spectrum.
I used 3' x 6' absorption panels behind my head in a 24' x 14' x 9 ' rectangular room with large archways at each end of the room and the speakers along the long wall and it sounded fantastic. Then a peep here at ASR used diffusers behind his head and said the room sucked with them there so he put them on the front wall. I think for acoustician laymen such as ourselves your approach of adding a panel or two at a time is a good approach.
Though placement and spacing do matter, central > peripheral, also multiple smaller pieces > single larger one, as per Toole (in Sound Reproduction) and Sauro as previously linked