# First reflection points for HT, and Music



## NBPk402 (Feb 21, 2012)

I just found this article that explains what I have always believed was true... A music room and a HT both need first reflection treatments. It is a good read for anyone that wants to know more about room treatments. There are quite a few books out there too, if you would like to read up on the subject for a more in depth review.

http://ethanwiner.com/early_reflections.htm


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## ajinfla (May 10, 2009)

Hi Ron,

I don't know how to sugar coat this, but the article you linked is complete nonsense, based purely on the authors beliefs, "intuition", sighted/biased preferences and is completely contradicted by science.
"Treating" a HT for your preference is ok because dialog originates primarily from a center speaker and the soundfield will still have ambient sounds generated from multiple channels and directions, even if direct.
This is quite different from 2ch reproduction, where ambiance and "center" information is generated by the front 2 LR channels.
Killing reflections there as advocated in the article is scientifically proven to be detrimental, despite the "intuition" and sighted "experiences" of the author.
Dr Toole explains all this is his book and lectures, via referenced "ears only" (blind) tests, as well as his own. The fact of the matter is that so called first reflections _enhance_ clarity. The reason is the phantom center created by the L-R has large amounts of lobing interference, which will spectrally alter the tonal balance:


> This coloration cannot be ignored in a situation where the direct sound is strong. Early reflections from different directions tend to fill the interference dip, making the spectrum more pleasantly neutral......Not to be ignored in any situation in which reflected sounds have been removed is the fact that the acoustical crosstalk that plagues stereo phantom images is present in its naked ugliness, without any compensation from reflected sounds


Another AES paper by Vickers explains it also:


> Yet another reason we do not consciously notice these comb filter notches is that room reflections and reverberation from all directions, while creating new cancellations of their own, nevertheless tend to smooth out the magnitude responses, filling in some of the missing information.
> As mentioned, early reflections perceptually fuse with the direct sound, adding more useful energy and increasing the intelligibility of speech [19]. The ability of room reflections to fill in the phantom center notches may be another reason for the improved intelligibility.


I'm just touching the surface here, because there is too much wrong about that article to waste my time debunking it all with real science. The final nail might be the old audiophile Golden Ear response that all those blind tests are flawed because they used "laymen", not true GEs, like those who work in Studios (aka Studiophiles), who can "hear" those "bad" reflections (with their eyes) easily and would have had completely different results (despite the fact that Toole did just that, tested Studiophiles also).
Well, more bad news. Based largely on the uproar Dr Tooles (et al) findings created amongst Studiophiles, researchers at McGill University decided to put that premise to the test: http://www.aes.org/e-lib/browse.cfm?elib=16640

Bottom line, one should "treat" rooms based on ones personal sighted preferences, but don't try to "validate" it otherwise.

cheers,


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## NBPk402 (Feb 21, 2012)

Thanks for posting up... I know that I have read all over that a room for music has different requirements than a HT, but in my setup we listen to music too, and it sounds great. I believe what makes our setup sound the way it does is mostly the room treatments that Bryan suggested we make. I am sure that if I had purchased from GIK that the treatments could be even more effective as theirs are designed differently than my basic ones.


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## Talley (Dec 8, 2010)

Most here will not agree with me and thats fine. In the past we have had "common" beliefs about treating for a 2 channel room would be different than a multi speaker movie enviroment. But nobody takes the recording into account. 2 channel is very critical as it creates a 3 dimensional space with two speakers and your room must be treated in a way to affect the the sound in 1. a minimal way and 2. an emphasizing way. What that means is enough treatment to silence the room (minimal) and enough treatment to enhance the room... kinda hard to grasp I get it, hard to explain... either way you got two speakers.

Multichannel has all the speakers it needs BUT in previous formats (movies here) the recording isn't "stereo'd" between all speakers nicely... the dialog is direct from center without any imaging/blend to the L/R or surrounds... I find this a problem because it creates a "dead" dialog sound... where it should be blended with ambience to mimic the room enviroment. Not all movies get it, some do. Flash forward to now... atmos/object encoding. Now the technology is grown to pinpoint a location and the decoding does the rest and uses all speakers to create that pinpoint spot. We are making advancements.

I look at treatment two ways. One... first wall the speakers hit is the most important wall... with the primary reflections. This exact point is the strong reflection back into the room. This should be treated. How is up to you. Everyone has a personal preference. My backwall to me was important and by treating it and the back/ceiling part in my room I effectively treated 70% of my room by controlling the initial very strong reflection back into the adjacent walls. I didn't treat the entire wall as I feel you need some reflection to create comb filtering improving the "space" sound. I kept absorption to a minimum and I am concentrating on "how" I think the reflection should be bounced back into the room. Symmetry is key here. Left to right no matter what should match. Front to back should be different so the waves get broken up one direction at the first wave and then another direction on the second wave. This will complete the treatment. No more than 15% absorption and no more than 35% diffusion based on total square footage of the wall vs. the square footage of the treatment. You must deduct any furniture blocking walls and/or count a bookshelf as diffusion as part as the equation.

This is what I came up with due to all the research I've come across and what I've read, my experience and my uncles input who is a 40yr audiophile with an amazing sounding room/system. I recently just treated my back wall/back ceiling and the difference was simply amazing. I'm not done either. The photos is just where I've gotten this past week.

I will be doing diffusion on the floor too and I'm upset I have carpet because that is 100% absorption on the floor. I'll be cutting a square out that covers my entire screen front stage area and will be putting hardwood floor in that area. I'll be placing diffusion panels on the floor in various spots to help as well.

I'm treating my room for "sound" with all considerations for all speakers involved.... not just for 2 channel or multichannel... I'm treating my room. I want my room to sound good. The rest is in the recordings and the system but neither of those can sound good if the room doesn't sound good. I found the primary reflections for all speakers and those are getting treated first and then the rest of the room based on above and so far it's going well.... although we are all objective to how we like things to sound. In the end... do what makes you happy.


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## NBPk402 (Feb 21, 2012)

I have been thinking of treating my surrounds as I did my mains, and get the first reflection points treated for the ceiling and side walls. I don't want to over treat them, but I think they should be treated too.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Here are a couple of articles on the topic, the first of which shows research basically along the lines of what AJ was saying.


Dispelling myths about comb filtering and early reflections
http://www.madronadigital.com/Library/RoomReflections.html

Acoustical effects of basic room furnishings
http://www.whatsbestforum.com/showt...ults-Thoughts&p=170293&viewfull=1#post170293]


Regards, 
Wayne


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## NBPk402 (Feb 21, 2012)

Wayne A. Pflughaupt said:


> Here are a couple of articles on the topic, the first of which shows research basically along the lines of what AJ was saying.
> 
> 
> Dispelling myths about comb filtering and early reflections
> ...


Thanks, Wayne... That is some excellent reading material!


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## MeatHanky (Feb 10, 2011)

This thread is a perfect example of why I love this forum!


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