Acoustic Guide
This section of the work is a buyer’s guide to acoustic treatment, not all kinds of treatment but the more common ones like Bass Traps, Diffusers, and Panel Absorbers. These types of acoustic treatment were chosen for comparison due to Everest (2014) book Master Handbook of Acoustics as panel absorbers are stated to be one of the more commonly used absorbers, and both bass traps and diffusers help with the low end frequencies and help scatter unwanted acoustical artefacts like flutter echo. (Everest, 2014)
This guide will be made with beginners and existing studio owners in mind, as well as Home and Commercial studios, the main areas of comparison are price, coefficients, and practicality, these were chosen because they are most relevant to the target audience of this guide and will be helpful for deciding which acoustic treatment is best for each person, for example a beginner home studio owner might value getting the most out of their money rather than coefficients or practicality whereas a commercial studio owner might value the coefficients above all else. (Everest, 2014; Owsinski, 2013; Yeary, 2014; Everest, 2014; Newell, 2017; Thomazelli & Bertoli, 2019)
The sites used to search for the acoustic treatment are as such: Amazon, eBay, Andertons, Thomann UK, and RPGeurope. These were chosen as they represent different markets and the level of expertise in their field, as RPGeurope will have professionally made acoustic treatment whereas Amazon could have a multitude of different acoustic treatment ranging from high quality to low quality.
Bass Traps
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JBER 4 Pack Acoustic Foam Bass Trap Studio Foam 12" X 7" X 7"
With the Amazon product, it is the top rated bass trap item on the site, it is also a 4 pack for £72.74 which works out at about £18 per bass trap which is not the cheapest as the eBay but still at an affordable price.
But a major downside to this product is its lack of AC (Absorption coefficients) acoustical data, which means there is no information about effective this product, making it very difficult to plan out the AC of the room and perhaps if you know how to perform AC tests then you could buy the product and figure out the coefficients but being that it is 72 pounds then it is an extensive gamble and it would be a waste of money if it was very ineffective product.
The description mentions it is made from a material called Acoustic Foam, which is made of polyurethane according to foamrite (n.d) but this is contradictive of the product description as they state,
“Acoustic foam is used to remove reverberation and sound reflections, provide sound insulation industrial and domestic applications suitable for sound studios. Unlike polyurethane foam, fiberglass and rock wool have health risks.”
Which either means that foamrite is lying or the sellers of this product are either lying or do not know what acoustic foam is actually made of and based this description off limited knowledge about what they are selling. Based on the foamrite web article, it is more likely that the sellers simply do not fully understand the product, which is fine as it does not state that they made this product so it will most likely be them reselling the product.
The main take away from this though is that now we can identify the AC of the product, which is, according to (Akustik, n.d)
125Hz: 0,25
250Hz: 0,50
500Hz: 0,85
1000Hz: 0,95
2000Hz: 0,90
4000Hz: 0,90
Which is quite an effective product, especially above 500Hz but being that this is a bass trap it is a nice benefit but would be better if the below 500Hz was around the .85 to .95 AC as well but is still quite effective and being that you get four it makes it even better. But it is still misleading on the sellers side as this information is not listed on the page which means the people who do not what to look for will not know whether this product is actually effective or not and being that the seller has shown evidence of not fully understanding the product, there might be a chance that the material it is listed as might not be the case and it might only what they were told so it is still a slight gamble if to whether it is worth purchasing.
4 Professional Acoustic Foam (1200mm+600mm) Bass Traps Sound Treatment
Next is eBays own 4 Professional Acoustic Foam Bass traps, which are the cheapest out of the bass traps as it is priced at £47.99 and it is also a 4 pack which makes these around £12 each which is very affordable and is the best product for getting the most out your money but just like the Amazon product, the AC is not mentioned in the products description which again makes it questionable whether it is effective or not.
Fortunately, this product is mentioned to be polyurethane in the description, which means that it also has the same AC as the Amazon Product. (Akustik, n.d)
125Hz: 0,25
250Hz: 0,50
500Hz: 0,85
1000Hz: 0,95
2000Hz: 0,90
4000Hz: 0,90
When buying this product, you get two 60cm x 28cm and two 120cm x 28cm which are bigger than the Amazon product, which is 36cm x 32cm for all 4 pieces which means that the eBay product covers more surface area in the corners of the room.
So far the eBay product is the better product as it has the same AC as the Amazon product but is near half the price and larger so it can cover more of the corners of the room and with an extra £23.24 you can get the eBay product twice to cover more area if necessary. But the same problem of not knowing if the sellers knows what they are selling is affecting this product also, but it is still the better product compared to the Amazon Product.
Universal Acoustics Mercury Bass Trap-300mm
Andertons’ The Universal Acoustics Mercury Bass trap 300mm is a bass trap that is shipped as a pack of 4 for £108.00, currently discounted to £99.00, or £24.75 each. Which is second most expensive bass trap from the selection, but due to still getting four instead of one, or two like the RPG and Thomann ones, it is not too bad in terms of value for money.
Andertons also does not give the absorption coefficients, but does give the NRC (Noise reduction coefficients) which the absorption coefficients of acoustic treatment in octave bands of 250Hz, 500Hz, 1000Hz, and 2000Hz, which are averaged to the nearest multiple of .05 (Farrell, 2006)
Which is quite confusing for beginners and people who do not anything about acoustics but despite that, the NRC of this bass trap 1.50 which is quite good as this means that this bass trap is effective at absorption frequencies around 250Hz, 500Hz, 1000Hz, and 2000Hz.
This NRC specification is not as effective as the AC specifications, as with AC you will know what exactly where within the frequency band where this treatment is effective and not effective which is help for planning what else might be needed whereas NRC only gives you an average of those particular frequencies which leaves you with holes in the planning what might be needed to compliment it.
Not being that it is a bass trap, thus it is going to be better at the lower frequencies, but the more detailed specifications of AC sheets makes it easier to know exactly what you are getting and how to plan around it.
t.akustik CBT-37
On the Thomann website the top rated bass traps are the t.akustik CBT-37s, coming in at £41 pounds for a 2 pack, they sit at around 37cm by 37cm, which is slightly taller than the Amazon product but smaller than the eBay product, which is okay but nothing that makes it stand out from either other products.
The main major downside though is the price, £41 just for 2 bass traps works out at about £20.5 for a single bass trap, whereas the amazon, eBay and Andertons ones are £18, £12, and £27 so despite being the third cheapest, you only get half the amount the others offer.
But despite this, it has 4.5 stars from 607 reviews and is the highest rated with the highest amount of reviewers so it must be good to certain degree, this website is also not too descriptive with its product as there is no mention of AC but does mention its material meaning using the same AC chart as before, we can see that the absorption coefficients is, (Akustik, n.d)
125Hz: 0,25
250Hz: 0,50
500Hz: 0,85
1000Hz: 0,95
2000Hz: 0,90
4000Hz: 0,90
Same as the Amazon and eBay product, it is the same material and therefore has the same coefficients, but when considering price and how many you get for the price these product is frankly not worth it since the coefficients is the exact same but is costing a lot more, there is nothing that sets this product apart from the others.
RPG Modex Corner
Lastly for the bass traps, is RPGeurope’s RPG Modex Corner. Which has shown in the page for this product, it is by far the most descriptive and offers the most insight into the product, this is generally the same for all of RPGeurope’s product pages.
The page consists of a problem, solution, applications, performance, absorption coefficients, installation, benefits, options and features, with an additional acoustic data tab which has graphs and tables of the AC of this product. All this information is really effective at letting the buyer know exactly what this product is about, what it will do and how effective it will do it. Perhaps a little un-inclusive for non-specialist individuals but still effective.
(Figure 1) shows the AC of the this bass trap, this was taken from the website, so it is the most up-to-date and accurate AC sheet for this product. And as shown, this product is quite effective at absorption from 80Hz to 200Hz and especially for 80Hz being 1.12 AC. And even beyond 200Hz it is still not bad as they are all still absorbing even a little amount which helps reduce the overall reflections.
Compared to the Amazon, eBay and Thomann products, the AC of this product is far superior in terms of lower frequencies, which is what bass traps mainly target, and being that this AC sheet comes from the manufacturer it is more accurate than the unaffiliated AC data sheet used to determine the Amazon, eBay and Thomann products. It also is more specific with its frequency bands unlike the other products.
It is clear that this product is the highest quality, but this quality comes at a high price. As this product is £199.68 for one bass trap, whereas the other products at least come in a pack of 4, or 2, this means that product is,
£126.94 more than the Amazon Product
£151.69 more than the eBay Product
£91.68 more than the Andertons Product
£158.68 more than the Thomann Product
Which makes this product very difficult to consider buying over the other products as yes, it has the data to prove it will be effective but will cost near £100 or £150 more just for one bass trap instead of four or two. Perhaps another RPG product will be more worth depending on the overall impact on the room, as one bass trap is not enough to properly treat a room.
Figure 1
RPG Modex Corner AC
Diffusers
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BXI Acoustic Sound Diffuser Panel 300 X 300 X 25mm
Amazon’s product is the BXI Acoustic Sound Diffuser Panel, a 4 pack of diffusers that all 30cm by 30cm, what is quite good about this product is that it is only £13.99, which works at about £3.49 per diffuser, which is very lucrative, but being that this product has no mention of its coefficients or scattering performance which means there is no evidence on how effect this product is other than the reviews it has, and it is reviewed at 4.5 stars but it is not hard evidence.
But being that this product is so cheap, there is not much of a lose if you want to take a gamble on this product.
4X NEW Quality white solid wood Diffuser
The eBay product is also a 4 pack and is also 30cm by 30cm and this one does give its scattering coefficients, this product is effective at 2460Hz to 4200Hz which will affect the high mids according to (audioissues, n.d), which is not too bad but could be offer more in terms of range, but it is still effective to see the products specifications be featured in the page, as now the buyer will know the effectiveness of the product and what they are buying.
But, that being said, compared to the Amazon product, this product is very expensive, as this product is £180, or £45 per piece. Now this is expensive and even on the original manufacturers website it works a little bit more on there as they listed it as £196 for 4 diffusers, but they do offer a custom size option for an extra £80s on the manufacturers site which is quite practical for the buyer if they need a very specific size.
Last thing of note is the shape of this diffusers compared to the amazon product, as this diffusers follows the technical design of a QRD (quadratic) Diffuser, which is a diffuser that has a load of different wells that are in varying heights which cause a plethora of phase shifts that make the reflected sound diffuse that controls the reflections that strike the diffuser. (Subwoofer-builder, 2020)
Whereas the amazon product does not follow a shape that has been scientifically designed to deliver a specific outcome, it does show that the design will diffuse the sound as the shapes on the amazon diffuser would reflect the reflections in a load of different directions and scatter them but to what degree is unknown. Where this eBay product has shown where in the frequency spectrum it is effective and is a shape that is scientifically proven to effective diffuse reflections. (Subwoofer-builder, 2020)
Hofa Diffusor natur
The Thomann Hofa Diffuser also follows the QRD design, it takes a different approach with the design as it is design to have wooden like wells instead of the eBay one that uses different sized wooden blocks.
Unfortunately, no coefficients or scattering effective is mentioned in the description of this product so there is no way to know the effectiveness of this product outside of the high reviews this product has.
Which brings on the next point of price, as this product is listed at £57 for one diffuser, which if you bought four like the other diffuser products mentioned above then it would come to £228 which is the more expensive than the other diffusers as well, which when there is no mention of the effectiveness of this product, it brings up the question, is this worth gambling on or even buying in general when the eBay product has its specifications and the Amazon product is extremely cheap and more practical in terms of getting the most out of your money.
RPG Omniffusor
RPG Omniffusor is another QRD designed diffuser, like the previously mentioned RPG product, this is very descriptive in its project page, out lining all the relevant information for this product.
Both (Figure 2 & 3) show the AC, diffusion, and scattering of this product and it also shows the effectiveness in different variations of the same product. Which is quite effective as it shows the outcomes from using this product and also offers choice so for example, the panel fabric on surface worked best for your situation then you could go with that and know what will do.
This product is £210.60, and 59.69cm by 59.69cm, which makes it double the size of the Amazon and eBay products but when considering that with the Amazon and eBay products you get a 4 pack of diffusers, it makes it difficult to warrant the purchase, it is a guarantee you will be getting a high end product which is sometimes best. It is also worth noting that if you spent an extra £17.40, you could get the Thomann product which is the same design and you get four diffusers but again without that data, it is hard to know if this product is really worth the purchase.
Panel Absorbers
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12 Pack - Acoustic Foam Panels, 2" X 12" X 12" Mushroom Studio Wedge Tiles
Amazon’s product is Mushroom Studio Wedge tiles, this product comes in a 12 pack and they are 36.5cm by 35cm in size. They are rated 4.5 stars from 1,249 reviews, the price of this product is £37.99, or £3.16 each, which is really good price for the amount of panels you get.
But as past trends, Amazon does not have any AC specifications in the description, meaning the use of outside AC data sheets will need to be used.
The product page mentions that it is made of acoustic foam, or polyurethane. (Akustik, n.d)
125Hz: 0,25
250Hz: 0,50
500Hz: 0,85
1000Hz: 0,95
2000Hz: 0,90
4000Hz: 0,90
Knowing this information is effective, but frustrating for buyers as they will have to find this information themselves and it could be inaccurate or flat out wrong.
Pro-coustix Ultraflex Wedge Acoustic Foam Tiles
The next product from eBay is the Pro-coustix Ultraflex Wedge, these are similar to the Amazon product as they share the same shape and material, as both are listed as acoustic foam or polyurethane but where this eBay product differs is in its price and value, as it is listed at £34.99 but you get 24 tiles instead of 12, meaning each tile is £1.45 which is £1.71 cheaper than the Amazon Product in terms of value for price.
So with a similar size of 24.49cm by 17.91cm there is not much of a different between the two except for size, making the eBay more favourable for purchase. It is also worth noting that pro-coustix has a website that has a listed AC of, (pro-coustix, n.d)
1000Hz: 0,85
5000Hz: >1.0
And with the AC data from the Akustik data sheet, that works out as an effective AC, making this very worthy of purchasing.
t.akustik HiLo-N40
Thomann’s t.akustik HiLo-N40 product is quite interesting as it is the only panel that is rectangular while the rest are just a square. What also is interesting is that instead of buying this product in bulk, you can only one at a time, but if we bought as many as the other two products, the price would work out as,
Thomann Product: £43.2 for 12 Panels, £86.4 for 24 Panels,
Amazon product: £37.99 for 12 Panels,
eBay Product: £34.99 for 24 Panels,
This is showing that for the same amount of panels, this product is far more expensive than the other two and even near double the amount for the 24 Panels, which does not compare well against the other products.
The size is quite large, as it is 100cm by 50cm so perhaps you could half as many of these panels since they cover more area than the others,
Thomann Product: £21.6 for 6 Panels, £43.2 for 12 Panels,
So it becomes quite cheap when only buying 6 panels, and overall it covers 600cm by 300cm whereas the Amazon Product covers 219cm by 210cm if you bought only 6 amazon tiles, but if we bought 12, it would come to 438cm by 420cm, so it is still more worth purchasing the Thomann product since it is cheaper and covers more area.
It is also the same material as the Amazon and eBay product so its AC is,
125Hz: 0,25
250Hz: 0,50
500Hz: 0,85
1000Hz: 0,95
2000Hz: 0,90
4000Hz: 0,90
So when considering the price, area that can be covered and the AC, this product is more worthy of purchasing over the Amazon and eBay products. Unless your room is too small then the eBay product will be more worth it since you get so many panels for very cheap.
RPG Absorbor
RPG Absorber is £109.44 for the 120cm by 30cm & 1” Thick product, which has a really effect AC from 631Hz and onwards, with most of them ranging above 1.0, which is complete absorption. And even below 631Hz, it is still an effective product.
The RPG Absorber also has a very detailed page, meaning that you will know exactly everything there is needed to be known about the product so you can properly plan out your rooms acoustic treatment.
When compared to the other products, the first major difference is price, as this product is,
£71.45 more than the Amazon Product
£74.45 more than the eBay Product
£66.24 (12 Panels) & £23.04 (24 Panels) more than the Thomann Product
Which when also considering that this RPG product only comes as a one pack, then it is considerably more expensive, and the product are worth a lot more in terms of value for money. But just like the other product, this one actually lists its own AC, shown in (Figure 4)
Plus the size of the RPG product is quite impressive, with only the Thomann product coming close to its height and being slightly wider than the RPG product. Whereas the Amazon and eBay products quite small compared to both.
Figure 4
RPG Absorbor AC
Conclusion
The main trends that are worth addressing is that the Amazon, eBay, Andertons and Thomann products have a very limited or unhelpful description of their products, some were not too bad like the eBay panel absorber product which had the coefficients of 1kHz and 5kHz but generally they were not helpful, this means that choosing these products for the acoustic treatment of your space would not give you many options to plan off unless you bought them, tested them yourself then wrote up a plan.
Now it is fortunately that the Amazon, eBay, and Thomann ones did mention their materials which allowed for an AC data sheet to be used to determine the products AC as this helped determine if the products were effective or not.
But there is a problem with this estimation AC using data sheets, that being the cut and depth of the product. As for example with the Amazon, eBay, and Thomann bass traps,
125Hz: 0,25
250Hz: 0,50
500Hz: 0,85
1000Hz: 0,95
2000Hz: 0,90
4000Hz: 0,90
This AC is good but for a bass trap having a AC of .25 at 125Hz is not very effective and would rather have it near the +.75, it is also worth noting that it does not show any AC below that 125Hz, which makes it hard to guess how effective the product could be in the low/sub frequencies.
Most likely the Amazon, eBay, and Thomann products have a higher AC at those lower frequencies due to their thickness but without any solid evidence there is no way of knowing. Whereas, the RPGeurope product has their products most up-to-date AC and other information that helps the buyer understand what exactly they are buying and how effective it will be. Meaning that despite the RPGeurope products being much more expensive, it is more of a solid bet to purchase their products due to knowing what you are buying.
The best bass trap out of the listed products will be the eBay Professional Acoustic Foam Bass trap, this is due to being quiet superior in price and practicality, with its AC being the only downside.
As for price it is the best value for money out of all the products and very cheap. It also covers more ground within the room being that two out of four bass traps are 120cm in height, so with this product you could be able to put two of the 120cm bass traps in either the front corners of the room or back and the other two 60cm in whichever you did not put the 120cms in, meaning that with this product you can effectively acoustically treat each corner of the room, whereas the other products are a lot smaller, for example with the Amazon product, to effectively acoustically treat one corner, all four bass traps will have to used which means you would need to buy the amazon product 4 times just cover each corner of the room effectively. (Owsinski, 2013)
For the Diffusers, the RPG Omniffusor is the best out of the list as it is superior in terms of its AC and practicality, of course price is major downside but is offset by the other two qualities. As despite being the most expensive product and getting only one diffuser instead of four, the amount of information going into this product before purchase warrants the price as the buyer will know exactly what is being bought and being that you do not need loads of diffusers unlike with bass traps. It is worth the extra money when knowing that the product will be effective and do exactly as it is stated in its description, unlike the other products where it is questionable whether the product will actually be good or not, and despite the eBay product having some specifications in its AC, it is only two frequency bands which leaves a lot of unanswered questions about the rest of the frequency spectrum.
Lastly, Panel Absorbers. The best is the Thomann t.akustik HiLo-N40 due to the price, practicality and somewhat its AC. As discussed above, you can buy 6 Thomann panels that covers a lot of area than the Amazon and eBay products, this also includes the RPG Absorber, as despite that being quiet large, it would cost £656.64 to buy 6 of the RPG panels, which yes does show its exact AC and is very descriptive, it is too expensive to warrant. Whereas the Thomann product, there are some estimations made with the Akustik data sheet, it is still cheap enough where you could purchase it and do your own testing if you are unsure about its AC effectiveness. Overall the Thomann products covers more area, has an estimation AC and is really cheap, plus is also highly reviewed.