Is this a test?

"How does it work? The various layers both absorb and diffuse the sound waves hitting them, so progressively less of the original source acoustic energy passes through each layer. This reduces the amount of energy hitting un-treated walls and other surfaces so there is less of the original source reflected back as unwanted room ambience to the mic. The Reflexion Filter also helps prevent any reflected sound reaching the back and sides of the mic. Its shape and size have been carefully tested to maximize absorption while keeping ‘coloration’ down to only around 1dB, and leaving the microphone’s polar pattern unaffected."


If you were testing a product's ability to control wall reflections that might come back towards the mic would you highlight a test in a room that doesn't have any reflections?




If you were going to promote a product as being capable of absorbing sound energy would you publish a graph that showed that absorption is absolutely minimal?



Please note that the graph doesn't relate to the test setup shown in the photo... they had to put the speaker on the other side of the "filter" to gather the data for that graph.




There are lots of well understood absorption products used in gobos... and none of them work well unless they are very thick... that's why you see that the product in question doesn't actually absorb anything. A fact which is clearly documented in the graph.  I wish they zoomed in on the vertical scale... but they didn't.

I guess they hope that people will look at it and say "see, no coloration" and it will never occur to them that what it really says is "see, no absorption"



Furthermore; (and this gets tricky if you don't enjoy acoustics) the conclusion drawn from the graph... that the filter doesn't "color" the sound is only applicable in an anechoic chamber.

Once you put that absorber in a real room with reflections... the reflections that will be absorbed the "greatest" will be those that arrive at their quarter wave peaks.

The "coloration", if you will, that any absorptive filter provides is the result of it's placement.

If you test in a anechoic chamber there are no reflections... so it seems like everything gets absorbed evenly.

If you test in a room with heavy reflections than you have some chance to absorb some of those reflections.... however the absorber, like all absorbers, can only absorb energy that is present at the filter. So anything that hits the filter at it's quarter wave peak will be absorbed more so than all the other sound waves that travel through it.

Thus, coloration will not occur until the filter is placed in a real room. If you want to de emphasize the idea that filters create frequency shifting results... you run a test in a room without any reflective energy.




To make a long story short. In my opinion, if you feel something like the Reflexion is beneficial to your setup... and I acknowledge that it may well be... you might want to try a heavy wool sweater some day. It may actually work even better.




all the best,
mike

I'd like to try one of the hoods that are fitted to public phone booths here.

They always sound OK when you use them, they're made of punctured sheet filled with foam.

They come in cheaper than these types of filters too. This kind of thing.

http://www.workplace-prod...industrial-phone-hood/

I'd like to get hold of a BT original fit one though they are vandal proof even.

I feel sure some simple experimentation would yeild better results than these reflexion filters.

Mike,  I don't think the test pictured or graphed is intended to show the amount of refection absorbtion.  I think it's intended to show that the filter does not affect the sound of the mic.

I find that when I'm being questioned in a room like that one, it's usually smaller and everybody looks very serious.  The jackets are a bit constricting as well.

I failed that test for sure.

My jar had jellyfish.  My throat is still burning.

I did anyway, just to be sure.  ...for the sake of realism. 

+1 for rockwool gobos...we are laden with them too.  And you are way off on the decade;-)

I am not sure... ?



Oh... now I get it. :-)