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Should I change rooms?

Discussion in 'Room Acoustics / Isolation / Treatment' started by DonnyThompson, Jun 17, 2014.

  1. DonnyThompson

    DonnyThompson Distinguished Member

    As many here know, I've been in the process of trying to improve the acoustics of the current room I am in.

    Last week, due to a family member moving back home (my mom is terminally ill and will now be in her own home with the aid of hospice and nursing) I now have another room I could use as an alternative to the room I am in now.

    The reason that the new room interests me is that because measurement wise,
    it seems to be fairly close to one of the Sepmeyer ratios; (in my case, it would be Sepmeyer's second ratio) which is:

    H X W X L__

    1.00 X 1.28 X 1.54


    Here are the dimensions of the other room:

    H X W X L
    ___
    8' X 9' 7" X 11' 8'


    Here are the resulting ratios:

    H X W X L___
    1:0 X 1.22 X 1:48


    Ratio Differences:

    H X W X L__

    -0.00 X -0.06 X -0.06


    As you can see, the ratios appear to be very close, BUT... I don't know that they actually are, because I don't know how crucial it is to be exact to these ratios... so that a difference of
    something as seemingly small as -0.06 could be a mile off in terms of the equation...and this is what I don't know....is it close enough to consider?

    Materials in the other room would be the same as the room I am in now; 1940's Gypsum Board on walls and ceiling, hardwood floors, 2 windows, one entry.

    My question is, will moving into this other room be a better situation for me in terms of dimensions, and, would it provide enough of a noticeable benefit to make it worthwhile?

    I know very little about "ideal ratios" (although I'm studying as much as I can) so I turn to the experts here to tell me what they think.

    I have no problem moving to the new room; nor do I have any objection to re-treating this alternate room accordingly. I guess I'm just looking for input as to whether it would serve enough benefit to make it worthwhile...

    Thoughts?

    d/
     
  2. Kurt Foster

    Kurt Foster Distinguished Member

    from what i recall reading Donny, sepmeyer ratios don't have to be exact. it's better to get as close as possible but a little off here or there isn't a deal breaker.
     
    kmetal likes this.
  3. Space

    Space Well-Known Member

    What I wish you would do, from this point forward, is to keep all posts related to this topic in the same thread. You have said a lot of things over the past month and they are all over the forum.

    It would be really,,,really helpful, trust me ;)

    Maybe change the thread name to something more accommodating to your situation.
     
  4. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    +1 on that, I am thinking of a graphic in Alton Everest's book where it showed the ratios, then the range of areas around that exact ratio that were considered fine. Everyone I've talked to just said that the ratios are a good guideline, but not an end all, be all. I'm far from an expert, but my thought would be when talking rooms of that size, the bigger the better, if for no other reason than a deeper bass response. I'd have to check, but I think it was in that same book, that it said to use the longest dimension, which would be diagonal, to figure out what the lowest frequency your room can contain is. I also might be imagining it in my feeble brain, I'm on two hours sleep after an 18 hr mix session that killed the mixers power supply, so I'm a bit hazy tonight, and probably should not be commenting at all.
     
  5. DonnyThompson

    DonnyThompson Distinguished Member

    You're absolutely right. My apologies. I'm going to limit this to one topic, one thread. Thanks, Space.
     
  6. Space

    Space Well-Known Member

    Room ratios have been around for decades and rooms in general have been designed to be pleasing visually and sonically by many builders/ architects. You only have to look around the building you are in right now to recognize this is not something new, it has been around you all your life you just were not aware of this.


    The inclusion of room ratios for an acoustical environment is different in that the ratios used have been tested so that the builder has a better starting place than a typical room ratio that a typical builder might use.


    Alton Everest ( Master handbook of Acoustics - 4th Edition) presents 3 of the most widely used ratios developed by L.W. Sepmeyer (1965) and M.M. Louden (1971)




    Height Width Length

    _______________________________ _________

    Sepmeyer A. 1.00 1.14 1.39

    B. 1.00 1.28 1.54

    C. 1.00 1.60 2.33


    Louden A 1.00 1.4 1.9

    B 1.00 1.3 1.9

    C 1.00 1.5 2.5


    It must be noted that when these ratios were being tested a ten foot tall ceiling height was assumed. In some detail, we will find out why this was an important aspect to this particular testing procedure.


    Based on Loudens first ratio “A”, 1.00, 1.4, 1.9 with a ten foot tall ceiling this would produce a room with the interior finished ceiling height of 10 feet with a interior finished width of 14 feet and a depth of 19 feet. This room will have a volume of 2,660 cubic feet. Plenty of height for the sound to expand and develop and exceeds the 1500 cubic feet room volume limit determined to be the least amount of volume a quality audio environment should have.


    (C.L.S. Gilford, Affiliation: British Broadcasting Corporation,“The Acoustic Design of Talks Studios and Listening Rooms” circa 1979, maintained that a “small” room based on the research done would be a room with a volume of 1500 cubic feet. Further he states “It is shown that a distinctive characteristic is that, because their dimensions are comparable with the wavelength of low-frequency sound, the sound field is characterized by strong simple standing-wave patterns which cannot be eliminated without eliminating the reverberation itself. It is shown also that for the audible effects are confined to those associated with simple axial modes and that, by careful adjustment of dimensions, provision of diffusion and the proper distribution of absorbing material, the worst faults can be avoided. “)


    An interesting thing happens when we look deeper into these ratios, when we look at the single components of the room and not the end result.


    The speed of sound at sea-level is considered to be 1,130 feet per second and in order to get the fundamental frequency of the height or width or length we have to use the equation F=1,130/2xD.


    The height of ten feet using the above equation will produce: 1,130/20=56.5Hz. This is important to know since 56.5 Hz relates to the note A1. It actually falls 1.5Hz past the frequency of 55Hz.


    The width of 14 feet using the equation F=1,130/2xD (1,130/2x14(28)) = 40.36Hz which closely correlates to 41.20Hz or E1 on a midi keyboard.


    The remaining length measurement 19 feet X 2 = 38 produces 1,130/38=29.74Hz, relates closely to 29.14 (A#0/Bb0)


    Using the 8 foot ceiling height and Loudens first ratio produces a room 8 feet tall, 11 feet and a few inches wide and 15 feet and a few inches deep. That is about the size of a typical bedroom or the living room in some homes.


    The consideration for having a balanced proportional room is valid and worth the effort to use in any sound related type room. A few things to consider along the way. The measurements that are obtained from the ratios define the interior side of the wall.


    In order to use these measurements, you must determine how much and of what thickness your interior sheathing will be. This allows you to step out the placement of the sheetrock or MDF/OSB or whatever combination you may use, in order to establish were the actual framing will be placed on the floor of your build.




    To that end, ratios are not scalable...they cannot be modified and expect the same results: Room Sizing Tutorial | Acoustics, Audio and Video | University of Salford
     
  7. DonnyThompson

    DonnyThompson Distinguished Member

    This is an awesome post, Space.

    Things I found very helpful - and very interesting:

    "Based on Loudens first ratio “A”, 1.00, 1.4, 1.9 with a ten foot tall ceiling this would produce a room with the interior finished ceiling height of 10 feet with a interior finished width of 14 feet and a depth of 19 feet. This room will have a volume of 2,660 cubic feet. Plenty of height for the sound to expand and develop and exceeds the 1500 cubic feet room volume limit determined to be the least amount of volume a quality audio environment should have."


    "The consideration for having a balanced proportional room is valid and worth the effort to use in any sound related type room. A few things to consider along the way. The measurements that are obtained from the ratios define the interior side of the wall."

    I'm going to attempt to merge all these different threads/subjects into one thread/topic.
     

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