More on acoustics

So, if a website says that thick acoustic glass can reduce by 42 dB is this what they mean?

That 110 dB will, inside the glass, be 68 dB?

So, for example, if my balcony gets 110 dB, then turning it into a glassed in conservatory will give me some 70 dB inside the conservatory?

Which will, given the next layer of the doors into the living room from the balcony, reduce down again to 50 to 60 in that living room? I’ve just checked, those doors do give a 10 to 15 reduction.

Have I got the way these measurements work right?

11 comments on “More on acoustics

  1. That’s the maximum – it will be less than that in practice. But you have the numbers the right way.

  2. A useful rule of thumb
    -6dB is half as loud
    -20dB is 1/10th as loud

    I’m not so sure at that in the ordinary mid range of sounds human ears clock this. Modern restaurants are loud because there are no tapestries or table cloths etc to absorb sound, and small differences can be annoying.

    As per previous comments, the most intrusive sounds are bass. These will go round corners, through thick walls, propagate underground, etc.
    It can be fixed. If you have a void under the ground floor you can isolate the floor, but you’ll have to have some floating connection of the floor to the walls. Likewise for joists on upper floors.
    Expensive and not easy especially for retrofit to a concrete structure, but worth looking at the options before investing in triple glazing and keeping the windows open.

  3. Yes, sound reduction is cumulative.

    For example, when I go to the range to shoot, I wear earplugs good for 25dB, plus earmuffs good for another 21, for a total reduction of 46 db.

    But note that 50 to 60 dB in that living room will still be noticeable.

  4. Agree with zut alors” Glazing will only really attenuate airborne sound. Which tends to be the higher frequencies. In most cases just shutting single glazing will reduce those a tolerable level. It’s the lower frequencies cause the most problems They propagate well through solids & the building fabric will resonate at some of them

  5. Agree with comments above, acoustic glass will do well in helping reduce airborne sound, but will do nothing to stop the lower frequencies that are getting in through the structure of the house.

    Also, ‘can reduce by 42db’ is not the same as ‘actually reducing by 42db in all or most scenarios’. But it will help a lot, albeit at a high cost. As long as you don’t have to open the windows!

  6. @Tim W

    imo you’re going to spend a shedload of money and still suffer

    Move or sort the source of problem

  7. (I) yes, the dB’s add
    (II) for you to get the benefit of the addition, the non glass walls need to have a reduction MUCH LARGER than the glass.
    (III) they probably don’t

    Sigh

  8. Even 70dB can be irritating. 100dB is not ‘twice as loud’ as 50dB – 50dB is normal conversation, 100dB is a very loud, busy, packed pub with everyone shouting at each other.

  9. 10db is a doubling

    42db is very thick glass.

    Use double glazing with two thicknesses, eg 8mm + 6mm with the thicker pane outside.

    Put carpet in the room.

    Use heavy wool curtains.

    Cover walls with rubber tiles.

    Make all doors and windows airtight.

    Wear ear plugs.

    You can get dB apps for mobile phone, bitt they’re not accurate. Calibrated equipment is expensive, but will give you a breakthrough over the whole spectrum.

    Why do you have to live there?

  10. It’s a lot more complicated than simple arithmetic.

    The question that must be asked is-a 42 dB reduction at what frequency? Typical human hearing is between 100hz and 12000hz.(plus/minus depends largely on age) 42db reduction at 20kHz for instance is next to useless.

    If you are talking glazing solutions how much “noise” is transmitted through metal mullions?

    As jgh said the dB scale is logarithmic not linear.

    Bottom line be very dubious about claims of large noise reductions-42 dB is huge. You are in the realm of double-glazed window salesmen here.

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