Room Dynamics and the Effect of Hard Surfaces

[Pepperamip]

My listening position has my head about 8in away from a rear stud wall, he puts me to shame tbh :)

Would I see any benefit making that wall as sound deadening as possible with say some acoustic tiles / matting?

I can position myself equidistant to my speakers (around 8 foot with a slight toe-in) and the speakers are about the same distance apart from each other with a big telly splitting the two. I'm currently considering putting a big heavy blanket over the telly to prevent unwanted deflections but am I taking it a step too far with the wall? My floor is carpeted and I have heavy curtains behind my system.

Has anyone seen any improvements softening walls / floors / windows?

[Sherwood]

My listening position has my head about 8in away from a rear stud wall, he puts me to shame tbh :)

Would I see any benefit making that wall as sound deadening as possible with say some acoustic tiles / matting?

I can position myself equidistant to my speakers (around 8 foot with a slight toe-in) and the speakers are about the same distance apart from each other with a big telly splitting the two. I'm currently considering putting a big heavy blanket over the telly to prevent unwanted deflections but am I taking it a step too far with the wall? My floor is carpeted and I have heavy curtains behind my system.

Has anyone seen any improvements softening walls / floors / windows?

I use Magneplanar speakers in a dedicated music room: a double bedroom. The room is a decent size but smaller than the rooms I am used to running Maggies in. I made a number of acoustic panels out of 100mm acoustic Rockwool insulation. One set is positioned behind the speakers. The other (smaller panels) are behind my listening chair at ear level. Together they provide just the right amount of "damping" to tame early reflections and smearing from back wall reflections.

Geoff

[Macca]

My listening position has my head about 8in away from a rear stud wall, he puts me to shame tbh :)

Would I see any benefit making that wall as sound deadening as possible with say some acoustic tiles / matting?

I can position myself equidistant to my speakers (around 8 foot with a slight toe-in) and the speakers are about the same distance apart from each other with a big telly splitting the two. I'm currently considering putting a big heavy blanket over the telly to prevent unwanted deflections but am I taking it a step too far with the wall? My floor is carpeted and I have heavy curtains behind my system.

Has anyone seen any improvements softening walls / floors / windows?

Yes. I have a big window right behind me, closing the (quite thick) curtains makes the sound improve noticeably.

[paulf-2007]

IN my dedicated room I have 4' x 2' x 2" panels behind my sofa, two upright and the third across the top of the other two. Top one angles away from the wall and touches the ceiling as the ceiling is low. Also have another 4' x 2' x 2" panel at first reflection by right speaker and another on the ceiling. The left speaker is by French doors with kilo serge wool curtains as used in vocal booths.

[Barry]

If you can manage it, ideally the speakers should be placed at a 'live' end of the room (i.e. an end with a large window or patio doors) and the listening position at a 'dead' end of the room (if that too has a window - close the curtains).

[mikmas]

Always found the bay window syndrome a problem with typical UK semis - and try to avoid setting up speakers on either side or facing them unless heavy drapes are to hand.

Years ago I worked for a firm who hired out heavy velvet curtains to venues for sound deadening purposes.
Biggest customers were modern conference centres with big glass areas to cover. They made a massive difference

[Markiii]

I had glass bookcase doors right behind me. Covering them with cork tiles (looks far less gash than it sounds) made a huge difference

[Pepperamip]

If you can manage it, ideally the speakers should be placed at a 'live' end of the room (i.e. an end with a large window or patio doors) and the listening position at a 'dead' end of the room (if that too has a window - close the curtains).Barry ive managed this to some extent where my speakers face out from a top to floor window but then i have patio doors just in front of my right side speaker (perpendicular) However the cuetains are always closed covering these by the time im listening to music.

I do have a big 1m squate painting behind my head too so i wonder if that does parrt of the job for me.


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[dave2010]

This also relates to the recent suggestion of trying different speaker positions to improve the sound from the speakers. Most of us don't have enough control over our rooms to be able to really judge. One room we have is a quite large conservatory - not good in terms of reflecting glass. However, on one occasion I was presenting an evening of recorded music to a society, so decided to try in that area. Because the space was relatively free from other furniture I was able to position the speakers quite carefully. Small differences in position did make significant differences to the spatial characteristics of recordings.

My suspicion afterwards that "ideal" listening rooms would have hardly any furniture, and be acoustically dead - so that any ambience from the recording could be picked up, yet such rooms would probably be horrible to live in. Also it may be that recording engineers and producers actually do expect users to listen in "normal" rooms, so don't actually mix in any additional reverberation. Listening to some recordings in a completely dead sound environment might actually be unpleasant, unless artificial reverb is added in within the listening environment.

Only a very small amount of artificial reverb would be needed, but it could make some recordings more enjoyable to listen to. I don't think many of us are shaping the sound within listenning rooms in that way, though.

Getting listening right for more people presents additional problems too.

[Macca]

My understanding is that the reflected high frequency sounds need to arrive at your ears shortly after the direct sound, too much of a delay and you get smearing and muddle. But if there are no reflected HF sounds at all it will sound dead with very little soundstage. So treating a room is a complex undertaking as you need to get into the goldilocks zone.

[dave2010]

My understanding is that the reflected high frequency sounds need to arrive at your ears shortly after the direct sound, too much of a delay and you get smearing and muddle. But if there are no reflected HF sounds at all it will sound dead with very little soundstage. So treating a room is a complex undertaking as you need to get into the goldilocks zone.
Indeed. Also there have over the years (from around 1925 onwards) been different approaches to spatial recording. Early experiments with multi-channel systems suggested that for a sound stage in front of the listener that four speakers (4 channels) were the best compromise - without increasing the costs of more channels - microphones, amps and speakers, that three speakers were quite good, and that the stereo which we now accept as the norm was satisfactory - but not as good as 3 channel systems. Different recording techniques also have an impact - some attempting to remove phase information (Blumlein style), while others using spaced microphones of varying degrees. Some recordings really mess with this.

It will also depend what kinds of music one wants to listen to. Recordings of live orchestras, soloists, bands in a "real" live environment may, or should, use different techniques from those of synthesised or artificially balanced music. Much material nowadays is effectively electronically processed - and I don't really know how recordings do manage the "ambience" - which is very likely to be "artificial" in any case.

Should end users rely on the ambience within recordings, or shape their own environments, either by furnishing, hard/soft surfaces, distance between transducers etc., or even control it using speakers and extra ambience systems - such as has been used in large concert halls - though to varying degrees of success?

[Macca]

There are too many variables to establish a 'One True Way' approach, I think. As you say we can't get beyond the variety of recording techniques, let alone the room. And then we are all looking for a slightly different end result from a subjective point of view.

[Pepperamip]

Theres alot of ifs and maybes for sure. If my head is near a flat wall and that wall is directly opposite my speakers will putting something on that wall stop or reduce sound bouncing back to my ears from behind? The sofa has to stay where it is.

If it would would i may mock up some panels of similar dimensions to my painting. I would even consider covering the whole wall if i can find something that doesnt look naff.

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[Sherwood]

Theres alot of ifs and maybes for sure. If my head is near a flat wall and that wall is directly opposite my speakers will putting something on that wall stop or reduce sound bouncing back to my ears from behind? The sofa has to stay where it is.

If it would would i may mock up some panels of similar dimensions to my painting. I would even consider covering the whole wall if i can find something that doesnt look naff.

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Yes, an acoustic panel or panels will reduce the rear wall reflections. I find that such reflections can "smear" the music and make it more difficult to follow detail.

I made a couple of panels for behind my listening position. I bought a couple of naff canvas prints and covered the front surface with 100mm acoustic Rockwool. I then covered the whole thing with an old cotton sheet which I affixed with a staple gun. The cosmetic appearance was tidied up with some simple stenciling and stipple brushing with black fabric paint.

It works well acoustically and doesn't look too bad either.

Geoff

[JohnG]

In general the methods to acoustially tune a disturbed air movement in a room are carried out using controls, through Absorbtion and Diffusion of soundwaves meeting reflective surfaces.
The basic intention is that the ear receives much of the sound projected directly from the speakers, with the goal for the ear not to receive a excess of reflected sound from surfaces within the room.
The control measures can be furthered if external interfereing noise,
i.e 'Road Noise' are having a noticable impact on the quality of sound being produced.
In general most individuals like colouration in their music replay presentation, so overkill on devices to control a rooms disturbed air movement will be unneccessary.
Carefully placed absorption panels, so that a void of about 100mm from a wall to absortion material is present, will allow for a double absortion of sound wave.
Diffuser panels will break up sound waves redirecting their travel away from the ear.
The end users ear is the key to identifying the overall effect of the controls in use.
So the applications of devices and perceived effect on the listening space are subjective to the individual, in relation to how much colouration they are willing to live with.
Even putting trust in a computer programme, with sound pressure measuring devices, will not always produce a result that suit a individuals preferences.
It may be a good starting point to create the desired control.
As a example a reverberation or ring created by certain frequencies can vanish immediately with correct placement of control devices, this would be classed a positive.
As a rule this field of learning is a DIY friendly place.
Most of the common used control devices are relatively easy to produce and with a little investigation, materials can be sourced cheaply.
If making a Insulation Absorption Panel, a 45Kg per cubic metre insulation is the recognised all rounder.
There are plenty of Diffusion Panels ideas out there, even plans with scientific calculations supporting them.
I have just seen the OP's image and seen that it looks like he is using his scatter cushions as additional absorbers.
As a alternative the records can be stagger stacked on the rack, in 50mm batches, with one batch projecting about 50 -100 froward from the original stack line, this wll serve as a basic type of diffuser.

[Pepperamip]

Thanks John, i often give up listening if for example its summer, i have the windows open and theres too much noise polution. I dont want to make the entire room dead but im sure a little

Geoff i like the idea of making my own panels so ive ordered some rockwool (120 x 60 x 5cm) which i will try naked in various positions. If i like the results i will frame and cover them and probably save myself a small fortune in the process.

An accoustic panel / tile v bare wall round mine.....whos up for it? ;)

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[Barry]

My understanding is that the reflected high frequency sounds need to arrive at your ears shortly after the direct sound, too much of a delay and you get smearing and muddle. But if there are no reflected HF sounds at all it will sound dead with very little soundstage. So treating a room is a complex undertaking as you need to get into the goldilocks zone.

Yes, it's called the Haas, or precedence effect: https://en.wikipedia.org/wiki/Precedence_effect .

I seems that the 'live end, dead end' school of thinking (that I mentioned) has now been abandoned.

[Macca]

I think that predates a lot of the research done in the last ten years or so. It's still basically right though.

[Pepperamip]

I seems that the 'live end, dead end' school of thinking (that I mentioned) has now been abandoned.[/QUOTE]

Not totally Barry as the first thing I will do is put the panels at the speaker end. My right speaker is in a corner and is causing a little boom so I'll have one on the right wall before the french door curtains and one directly behind the speaker. I'll do the same with the left speaker too (except just the one panel behind as this one is in the middle of a long wall) I'll try the additional panels on the rear wall afterwards and see if that improves things or not. Nothing will be permantly fixed until I'm happy but I appreciate the live end / dead end approach you've highlighted.

[Macca]

This is worth a read - if only to get an idea of how complex it all is:

https://www.audiosciencereview.com/forum/index.php?threads/overview-and-approach-to-room-acoustics.75/


'How many singers do you know that like to sing outside where there are almost no reflections? Have you tried to sing yourself there? Fact is that some of these effects are totally non-intuitive. We think a reflection is a bad thing. But clearly no singer thinks that. I know it is hard to let go of these notions but let go we must'

[Sherwood]

Thanks John, i often give up listening if for example its summer, i have the windows open and theres too much noise polution. I dont want to make the entire room dead but im sure a little

Geoff i like the idea of making my own panels so ive ordered some rockwool (120 x 60 x 5cm) which i will try naked in various positions. If i like the results i will frame and cover them and probably save myself a small fortune in the process.

An accoustic panel / tile v bare wall round mine.....whos up for it? ;)

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It is a good idea to experiment with placement of acoustic panels, but you might find the 5cm (50mm) Rockwool to be too thin for the task. From what I have read, the 100mm Rockwool is the right stuff for the job. You could of course, double up on the 5cm stuff, but it is more difficult to make a panel that way. This is the stuff I used. https://www.travisperkins.co.uk/Rockwool-RWA45-Semi-Rigid-Acoustic-Insulation-Slab-100mm-x-1200mm-x-600mm-%282-88m2-pack%29/p/961938 You get four slabs in this pack.

Geoff

[Pepperamip]

This is worth a read - if only to get an idea of how complex it all is:

https://www.audiosciencereview.com/forum/index.php?threads/overview-and-approach-to-room-acoustics.75/


'How many singers do you know that like to sing outside where there are almost no reflections? Have you tried to sing yourself there? Fact is that some of these effects are totally non-intuitive. We think a reflection is a bad thing. But clearly no singer thinks that. I know it is hard to let go of these notions but let go we must'

Interesting read that Martin, you can almost create problems that aren't really there and change things that are actually making your system more enjoyable to listen to. I'll soon find out I suppose.

My minimum goal is to reduce some of minor boom from the right channel, If I can also tighten-up/clarify (or whatever you want to call) the sound with some minor additions elsewhere around the room then great if not, no harm done. A good little experiment to undertake either way.

[Sherwood]

Thanks John, i often give up listening if for example its summer, i have the windows open and theres too much noise polution. I dont want to make the entire room dead but im sure a little

Geoff i like the idea of making my own panels so ive ordered some rockwool (120 x 60 x 5cm) which i will try naked in various positions. If i like the results i will frame and cover them and probably save myself a small fortune in the process.

An accoustic panel / tile v bare wall round mine.....whos up for it? ;)

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I should mention that you need to be careful when handling the Rockwool. It is not something you want to be handling without gloves and you need to avoid breathing in the fibres. If you are experimenting with the placement you should try and find something to cover the "bare" panels on a temporary basis. When I made my panels I used a thin membrane type dust sheet to seal the panel and then a cotton outer cover for cosmetic purposes.