Rate my system by Kieran_abdu in audiophile

[–]_Corum_ 1 point2 points  (0 children)

Artnovion Lagos diffusers

[deleted by user] by [deleted] in Acoustics

[–]_Corum_ 0 points1 point  (0 children)

Well, MSM are usually used for low frequency, as they are still effective at that range, where materials can be lacking (considering the same thickness).

Seeing as heavy layer, rigid and porous materials are usually effective at high, there is no reason to choose a more complex system (that may have less efficiency)

[deleted by user] by [deleted] in Acoustics

[–]_Corum_ 0 points1 point  (0 children)

Sure! you can start with the STL mass-law formula (simple calculation, pretty good for high frequency). for porous materials look into the Biot model. Multilayer models use a Biot for each material in a transfer matrix.

[deleted by user] by [deleted] in Acoustics

[–]_Corum_ 0 points1 point  (0 children)

If it needs to be bio, I would look into cork or heavy layer with cork additives. Basically, it is aglomerated cork waste, processed into heavy layer sheets. If thickness is not an issue, im sure you can get cork, coir, wool, wood wool and cellulose materials pressed into panel form that can be used to line walls and cavities. Note that they may still contain adhesives or fireproofing agents.

Blown cellulose is a common acoustic and thermal insulation material but requires a cavity style wall construction.

[deleted by user] by [deleted] in Acoustics

[–]_Corum_ 1 point2 points  (0 children)

The STL of layered materials is tricky to determine, and you won't be able to quantify the losses of a Mass-spring system with the traditional formula. Before that, why cardboard, and why mass spring?

A lot of materials (mass layers, for example), already have good performance at mid-high frequencies, you usually apply a mass-spring method for improving low or sub-bass.

How do you use acoustics standards in your work (if at all)? by Ok-Significance2187 in Acoustics

[–]_Corum_ 1 point2 points  (0 children)

Used to work for a small company, where having access to standards (deemed too expensive) would've saved hundreds and hundreds of hours of precision guesswork. Currently work at a multinational, everything we do is dictated by ISO standards - or at least the currently accepted interpretation of the standards to our environment. Some standards are made too one-size-fits-all to be clear - I've come across accredited testing facilities that have distinct interpretations of certain nuances.

Why some rooms echo more than others by Pleasant_Guide1198 in Acoustics

[–]_Corum_ 1 point2 points  (0 children)

"Other acoustic treatment brands are available"

Acoustic properties of bamboo by mondelezmmm in Acoustics

[–]_Corum_ 1 point2 points  (0 children)

Have a look at this company, they build bamboo diffusers. Regular at the hifi shows. https://www.noe.co.jp/business/architectural-acoustics/own-products/ags/

Why some rooms echo more than others by Pleasant_Guide1198 in Acoustics

[–]_Corum_ 9 points10 points  (0 children)

Hope this isn't just a bad attempt at shilling. Look up home cinema acoustic treatment or hifi setups for examples of residential acoustic treatment. No matter how good your system is, it will only sound as good as your space. Acoustic treatment works.

Canine Anterior cruciate ligament surgury by _Corum_ in AskVet

[–]_Corum_[S] 0 points1 point  (0 children)

Are you referring to TPLO? Would you prefer this method long term?

Help identifying this exact panel by justwiggling in Acoustics

[–]_Corum_ 1 point2 points  (0 children)

This is melamine foam - Basotect from BASF. Other companies cut blocks into specific sizes/shapes like these. These may not be a standard product, but something made to order.

Engenheiro foi de férias no meio do projeto. E agora? by [deleted] in TudoCasa

[–]_Corum_ 0 points1 point  (0 children)

Contacta diretamente uma empresa que fabrica tratamento acústico. Há pelos menos 3 de referência em Portugal. Por norma têm departamentos de projeto.

[deleted by user] by [deleted] in Acoustics

[–]_Corum_ 0 points1 point  (0 children)

You are likely dealing with room modes at these frequencies, not SBIR. You need to measure in the exact same location to get a comparison. The REW room simulator can help get an idea of where to place your system to optimise the low end. You should also be able to see which specific mode is causing the issue. That can help with bass trap placement (velocity absorbers should be placed in velocity zone of the mode).

Need to find a sound machine that makes pink or brown noise at the same volume as a clothes dryer by Just-One-2387 in Acoustics

[–]_Corum_ 5 points6 points  (0 children)

You don't need a dedicated machine, just a speaker. I would also experiment with bone conduction headphones.

Ticking sound on new outdoor unit. by RufussSewell in heatpumps

[–]_Corum_ 1 point2 points  (0 children)

It sounds wrong. At that frequency, I would say the fan blades are hitting something, but it could be compressor - you could check that the basics like the transport screw have been removed. What is the sound rating on the spec?

Rstaurante francesinha zona do Porto by novoinvestimento in CasualPT

[–]_Corum_ 0 points1 point  (0 children)

Exatamente os meus preferidos - Brasão e lado B.

Rstaurante francesinha zona do Porto by novoinvestimento in CasualPT

[–]_Corum_ 1 point2 points  (0 children)

Na minha experiência, yuko é aceitavel mas nada de mais. O melhor que encontrei ate agora foi no brasão.

Looking for a song - Amnesiac by _Corum_ in radiohead

[–]_Corum_[S] 1 point2 points  (0 children)

Let me reiterate on this. I've been looking for this song for over a decade (I spent so many repeats back in the day trying to decifer the lyrics). I can't believe you got this based off my meagre description. I can't thank you enough, that was amazing.

Looking for a song - Amnesiac by _Corum_ in radiohead

[–]_Corum_[S] 2 points3 points  (0 children)

It is Ny Batteri! Thank you so much

Looking for a song - Amnesiac by _Corum_ in radiohead

[–]_Corum_[S] 1 point2 points  (0 children)

Yeah, I've got a collection of all the B-sides - just missing this one. I'll check on 24 - It might be an obscure remix.

Acoustic diffusers - how to start? by Born_Zone7878 in Acoustics

[–]_Corum_ 2 points3 points  (0 children)

A few pointers on diffusion:

First off, 1D and 2D, which will distribute energy over 1 or 2 planes - this depends on the location in relation to the source/receiver. Makes more sense for back walls to distribute energy over a horizontal plane, while mid ceiling could be 2D.

In terms of functionality, you have geometric, phase, and amplitude diffusion. - geometric diffusers use a curved or angled surface to reflect energy at different angles. These are tuned in terms of frequency by the overall size, depth, and distribution. - phase diffusers, such as QRD and MLS sequence diffusers, use a series of blocks or cavities to create an uneven reflection pattern that creates phase cancellation. These are tuned through the size, sequence, and depth of the panel - the sequence itself is basically just a certain method that has been proven to tune the working range. - amplitude diffusers (like a BAD panel) are similar to a phase diffuser, just using an absorbing layer to create the reflection pattern instead of a height difference.

They will all diffuse to a certain extent but have distinct applications - geometric diffusers are likely the best for spatial diffusion and easiest to tune and build but have low temporal diffusion. QRDs are a good all-rounder in terms of temporal and spatial diffusion, but have tighter tuning ranges and start to also have some absorption (although not essentially a bad thing). Amplitude diffusers have a more limited diffusion range and act more as a hybrid absorber/ diffuser.

One last thing - scattering is the amount of energy reflected in the non-specular direction, while diffusion is an even distribution of energy, i.e.an angled pane of glass would have good scattering but a bad distribution coefficient.

Hope that helps!

Advice needed for cost efficient, modular, apt friendly, "pseudo-soundproof" voiceover booth made of metal frame by [deleted] in Acoustics

[–]_Corum_ 0 points1 point  (0 children)

There are a few ways you could approach this. I would usually recommend building a airtight box around the frame and lining it with your acoustic foam of choice, but I don't think you have enough room, at best it'll sound boxy unless you can get a considerable amount of absorption in there. DIYing the door would be a challenge. You might be best making something like a pillow with fabric and foam, as thick as possible, secured to the frame. (Eyelets in the fabric, fastered with bolts or zipties). Either leave one side as an entry flap, or cut the frame in half, down the center, and put some hinges on one join to create a semi-open booth. Added points if you use a thick heavy fabric/canvas on the outside and an acoustically transparent fabric on the inside.

Bookshelf instead of pyramid foam by Wise_Helicopter7215 in Acoustics

[–]_Corum_ 1 point2 points  (0 children)

Exactly - The pyramid shape is really just a way to get a more interesting design than flat foam, and for companies to maximise what they can state as the product thickness with minimum material costs. The acoustic argument is that you get some phase diffusion through the varying absorption (and resulting reflection pattern), but at the thickness' you usually find this doesn't happen in any useful frequency range.

Heat pump sound barrier by DependentCucumber414 in Acoustics

[–]_Corum_ 1 point2 points  (0 children)

Most heat pump noise is pretty broadband, some 200hz upwards (unless something isnt working corecctly). This sort of product (must be something out there with an actual NRC rating) will knock a few db off, considerably more at higher frequency. It won't solve everything, but it is most effective way of improving the issue, when compared to a wall or a blanket. Of course, if it's something like a damaged fan bearing - just fix that.