Pros and Cons of Sealed Listening Rooms

[JackD201]

I've seen this sort of geometry used in recording studio builds. Having the non-parallel side walls further apart at the back of the room than at the front of the room tends to direct the first sidewall reflections behind the main listening area. In other words this is an effective technique for minimizing early sidewall reflections WITHOUT absorbing them, so that energy survives to become later-arriving reflections after another bounce or two.

Imo this avoidance of early sidewall reflections effectively "disrupts" the small-room-signature which would normally tend to super-impose itself atop all of the recordings. So you hear "less of the room", but because the room is using geometry instead of absorption to accomplish this, the reverberant field is still strong enough for you to hear "more of the recording venue". Indeed this is one of the reasons WHY recording studios often use this type of room geometry: So that the engineers can clearly hear the recording venue cues on the recording, instead of having those venue cues (whether real or synthetic) masked by the acoustic signature of the much smaller room they are mixing or mastering in.

Yes Duke. Absorption is typically applied to the 2nd reflection points and in a trapezium the rear is diffused. The wall splay which has a minimum effectivity of 2" for every 10' of length is the rarest in use but has proven to be very effective. Many forget that reflection whem used to re-direct ttop end energy is also an option. The same principle can be used in a rectangular room with an array of slanted panels running down the sides of the first 2/3rds of a room.

 

[JackD201]

I'm wondering if we can assume that if voices sound good in a room that it will be a good room for audio, and vice versa.

No need to assume. The answer is yes. We are evolved to be most sensitive to the human vocal range after all.

Well, with one exception. It has got to be somebody else's voice not your own. A good room should allow full intelligibility at max distance within the space. If your own voice sounds better to you when you speak or sing, you have too much reverberation, like singing in the shower. That's the reason singers use stage monitors, headphones or IEMs fed with their own vocal channel, to hear their "external" voices or put another way:, how others are hearing them

 

[JackD201]

I'll chime in on with my own views tomorrow as I have had both open plan and dedicated spaces. I'm dead tired now,

 

[spiritofmusic]

No need to assume. The answer is yes. We are evolved to be most sensitive to the human vocal range after all.

Well, with one exception. It has got to be somebody else's voice not your own. A good room should allow full intelligibility at max distance within the space. If your own voice sounds better to you when you speak or sing, you have too much reverberation, like singing in the shower. That's the reason singers use stage monitors, headphones or IEMs fed with their own vocal channel, to hear their "external" voices or put another way:, how others are hearing them

Jack, tricky when the hobby is full of people who love the sound of their own voices, and rarely listen to advice Lol.

Seriously as well, testing for slap echo also needs to be done by SOMEONE ELSE.

So, intelligiblity and slap echo. Need another human w you.

 

[sbnx]

Extremely interesting position. Did you also try switching the speakers so that the tweeters were on the inside? Did it sound as though the soundstage was back in the hallway or dining room? Can you describe the sound for us?

Hello Peter, I didn't switch the speakers tweeter position as I was just wanting to prove that my idea would work.

The sound was very open an airy with good soundstage. There was depth that was appropriate to the recording. Meaning a small jazz ensemble would be spread out behind the speakers with perceptible layering of instruments. On Orchestral pieces the depth was greater. The sound of this system was vastly different to what is in my dedicated room. Some people use the term "lively" but to me it is acoustically noisy. In the dedicated room the noise floor is much, much lower and with acoustic treatments much greater detail can be heard as well as better defined soundstage/images.

In my opinion it was much easier to get great sound with the system turned in this direction as compared to with the speakers along the wall. Where I live many of the houses have very open floorplans. A lot of them even have a 2nd story game room that is open to the 1st floor. I used this same idea to set up a 2 way speaker system for a person on the 2nd floor. He had the speakers along the wall and was struggling to get good sound. We turned the system 90 degrees so the speakers were along the open railing with the backs firing out into open space with the living room below. Much easier to get great sound. He says people come over and look at his system and think "that's not going to sound good" but then are surprised with what they hear and how good it sounds.

I realize this may not work for everyone but it is another tool in the box to get great sound.

~Todd

 

[JackD201]

Jack, tricky when the hobby is full of people who love the sound of their own voices, and rarely listen to advice Lol.

OMG that was funny Hahahahaha!

 

[spiritofmusic]

OMG that was funny Hahahahaha!

I should know, I'm as guilty as much as anyone else.

 

[Exlibris]

No need to assume. The answer is yes. We are evolved to be most sensitive to the human vocal range after all.

Well, with one exception. It has got to be somebody else's voice not your own. A good room should allow full intelligibility at max distance within the space. If your own voice sounds better to you when you speak or sing, you have too much reverberation, like singing in the shower. That's the reason singers use stage monitors, headphones or IEMs fed with their own vocal channel, to hear their "external" voices or put another way:, how others are hearing them

I think there are some relevant points here but mostly it's just an interesting read:

https://www.bbc.com/future/article/20190729-how-the-sound-in-your-office-affects-your-mood

"Mainstream architecture typically considers a building’s sonic voice only in the construction of concert halls, where acoustic perfection is key. The idea that you can take this a step further, and have a building itself act as a sort of musical instrument that envelops people, that’s capable of inducing feelings of tranquility, exhilaration, tension or even a trance-like state is unusual. However, it isn’t unknown." (my emphasis)

The key seems to be the shape of the ceiling.

 

[kach22i]

I think there are some relevant points here but mostly it's just an interesting read:

https://www.bbc.com/future/article/20190729-how-the-sound-in-your-office-affects-your-mood

Yes, very interesting and thank you for posting it.

..........noise annoyance itself has been linked to depression and anxiety. .....

Since moving from the city to the country along a beautiful river my stress levels have dropped.

Friends say I look more relaxed.

I tell them that I feel like I won the lottery I'm so pleased with my new place - it's quiet.

Thanks to virtual reality systems, architects are beginning to listen to how the spaces they design might sound like through “auralisations” of structures using acoustic modeling software like Odeon. Such auralisations are used to prevent sound transfer between spaces and make design decisions such where to place absorption, diffusion or reflective surfaces.

Okay, when is this going to trickle down to us audiophiles, or has it already?

What is ODEON?
https://odeon.dk/product/what-is-odeon/

Odeon is the most comprehensive software for room acoustics. Use the ODEON software for simulating and measuring the interior acoustics of buildings. With the appropriate treatment, outdoor situations can be studied as well. Given a 3d-model and materials (surface properties), the acoustics can be predicted, illustrated and listened to. Sound reinforcement is easily integrated into the acoustic predictions. ODEON uses the image-source method combined with a modified ray tracing algorithm.

ODEON is known for its easy workflow, fast calculation times and high accuracy. The easy workflow makes it fast to begin using for the most common tasks, the fast calculation time makes iterative design processes possible, and the high accuracy makes it trusted by a large community of engineers worldwide.

 

[andromedaaudio]

I found here an interesting article , not to complicated .
It also has a so called optimal room dimension graph.
According to him it is advised to have a minimal 5 degrees off set of the room walls , not only the side walls but all .
My room could be then for example to fit good in this graph , 3 meters high 4,5 wide 5,25 meters long.
And a flooting room in a room off course that would be mandatory for me
https://studiowizard.wordpress.com/...cs-explained-this-is-what-you-need-to-know-2/

 

[andromedaaudio]

If i would use the louden ratio for optimal room dimensions it would be : Louden ratio of 1 1.4 1.9 .
3 meter high ceiling gives 4,2 m wide 5,7 meters long.

Plus i would use off sett walls min 5 - 10 ° degrees or something like that for side walls and then 5 ° + for the ceiling .
The front and the back preferably divided / split and angled construction wise , or else with a big diffusor.
That would then be the raw construction for example in which one can can add bass traps do all kind of things .
,diffusors and some absorption can be done later .
Just a bit of thinking

 

[andromedaaudio]

According to gearslutz 11 foot height is minimum so that would then give this :

From gearslutz forum ( recordingforum)

I'm going to build a studio in my garden and was planning on using the Louden ratio of 1 1.4 1.9 I plan to have a ceiling height of 11 foot (I read this was the lowest acceptable control room height) Therefore the dimensions will be : 11 foot high 15 foot 4 wide 20 foot 10 long (3.353 m x 4.694 m x6.370 m).

Then there is golden ratio ; Ratio 1/1.62/2.62.

Sep meyer ratio : Sepmeyer 1 : 1.6 : 2.33.

Another interesting link : http://www.acoustics.salford.ac.uk/acoustics_info/room_sizing/?content=best

 

[andromedaaudio]

Sorry to hijack your thread a bit ron , but all these things mentioned would nt be pôssible with an open space, so another reason for a closed / sealed space , i fully agree with the below:

Room modes, if well controlled, will support the output of the sound system. They exist from low frequency to high frequency. Treatment is always almost needed to reduce the decay time of low frequency modes. An ideal room ratio will not avoid the need for treatment, but it may make the amount of treatment needed a lot less. If you were unfortunate to have a small cubic room with degenerate modes that are sparsely spaced then a lot of surface area treatment will be needed to tame them. Therefore you can see that adhering to the optimum room size and room ratios can lessen the need for lots of treatment

https://www.gearslutz.com/board/stu...building-room-according-best-room-ratios.html

 

[kach22i]

I'm not sure where I saw it, but one website on room acoustics has Dipole loudspeaker rooms a little shorter than Monopole loudspeaker rooms.

I thought it was the below website, but maybe not. Will try to find later, just want to bring up the possibility that perfect room dimensions are loudspeaker type dependent.

http://www.linkwitzlab.com/rooms.htm

 

[microstrip]

One of the nicest things in the net is that with appropriate search we can always find something that supports our desires ... Optimum room dimensions is an extraordinarily controversial subject and I find no reading on this subject is complete without reading Chapter 13.2.1 Optimizing Room Shape and Dimensions of the F. Toole book.
It summarizes most theories - one nice thing is that graph he presents of the Bolt ratios is much friendly than the one presented in a post above, supporting my own room - but clearly analyses how mystifying can be these famous ratios and blessed formulas for room evaluation.

I quote "Fazenda et al. (2005) investigated subjective ratings and technical metrics, finding that “it follows that descriptions of room quality according to metrics relying on modal distribution or magnitude pressure response are seriously undermined by their lack of generality, and the fact that they do not correlate with a subjective percept on any kind of continuous scale.” And then Toole explains why.

 

[andromedaaudio]

Okay microstrip , but you gotte start somewhere .
I have a solution though , moveable side walls and backwalls / frontwalls and adjust your roomvolume on listener preference .
Change angles , whatever you want
Move them back and forth and adjust

 

[microstrip]

Okay microstrip , but you gotte start somewhere .
I have a solution though moveable side walls and backwalls / frontwalls and adjust your roomvolume on listener preference .
Change angles , whatever you want
Move them back and forth and adjust the volume

IMHO if starting a new room from scratch without any constraints we should aim at the golden ratio and length longer than 8.5 m - it will not hurt!

 

[andromedaaudio]

Thats your preference which i fully understand
But for good pressure built up you cant go to far back i think , otherwise you make it to big , it depends also on the speakersize that is used off course.

 

[Ron Resnick]

IMHO if starting a new room from scratch without any constraints we should aim at the golden ratio and length longer than 8.5 m - it will not hurt!

+1

And a high ceiling.

 

[Ron Resnick]

This is slightly off-topic, but what about rooms with low ceilings. Ive always assumed a 9' ceiling would sound better than 8' and 8' better than 7'. I ask because most of the older homes in my area have basements with low ceilings.

It doesn't seem to factor into room dimension calculators as a advantage, but I personally think that high ceilings are very valuable.