Advice for continued efforts to reduce sound transmission into a bedroom

[gyoenastaader]

Recently I bought a new construction home, and after moving in I was fairly dismayed at how loud the master bedroom is. The home is a quarter mile to the closest busy street, but it sounds like I'm living ontop of a highway. I can hear constant low rumble, and an "accelerating" noise. 

The other bedrooms are rather quiet, so it has to do with something with the orientation and acoustics of the home. After some investigating, I realized I am hearing an echo coming off some apartment buildings behind the house. Front yard is rather quiet, while the backyard is loud!

The room has two exterior walls that face the side, and rear of the house, that I'm confident the majority of the sound is transmitted through.er (There is a vented attic above the room with 18" of blown loose insulation.)

So on the two exterior walls, I double hung 5/8" drywall with green glue between the sheets. (2x4 16" OC with pink insulation, exterior is 1/2" ply with vinyl siding). This helped a bit, by dropping the perceived average noise level. It is still rather hard to sleep comfortably in the room as the noise is unrelenting. So I installed large acrylic window inserts (Indows), and this seemed to do almost nothing. Investigating further into Indows, I realized their inserts are fairly poor performers for low frequency noise. https://indowwindows.com/wp-content/uploads/2016/09/Indow_Field-Sound-Transmission-Loss_081116.pdf They actually came make very low frequencies worse at 3 inches. (Surprisingly that is the space I have to work with)

This now brings me to the real portion of this post, I have seen several times on this forum the avocation for MagnaSeals acrylic panels. At this point I am very wary that this will work for me. The idea between MagnaSeal and Indows are similar, as with the materials. This leaves me with SoundProof Windows which are the next option. Does this seem like an appropriate application for SoundProof  Windows? Finding information from someone that has gone from acrylic to SoundProof Windows has been difficult.

[Randy S]

This is actually quite common,  depending on your window size 1/8" is not nearly enough mass to give you value in the lower frequencies.
Mass / gap / mass
this is what determines values plus you have to take a few other variables in to consideration as well.
like size of window, bigger the window means bigger the speaker.
does the existing window have any leaks?
and as you pointed out gap size...you have 3" which with enough mass from the insert would normally yield a good reduction.
I like to use 3/8" minimum for traffic noise...
I also am not a fan of the bulb perimeter seal this is a weak spot in the system.

Based on achieving a full value of room noise reduction there are a few more things to discuss, which you are aware of like the attic vent..
Give me a call direct and lets discuss the total bubble to achieve a good nights sleep.

Randy S.
760-752-3030
randy@soundproofing.org
 

[gyoenastaader]

I like to use 3/8" minimum for traffic noise...

I neglected to add this information, but the Indow insert is 3/8" acrylic. But this is way I am wondering if I need a beefier window cover to help with attenuation.

As an aside, I was watching a kid dribble a basket ball through the window and could clearly hear a low frequency thud. Almost like a mallet hitting a board. I went into another room that is not treated and could hear that thud, and a higher pitched twang. So the Indows do work just at higher frequencies.

I agree though that I am not a fan of the press fit system, as it has a tendency to tear. I actually had two of them replace at no cost due to bad fittings or torn seals.

like size of window, bigger the window means bigger the speaker.
does the existing window have any leaks?

One wall has three 55"x35" windows, so fair size, but it accounts for about 45% of the wall area.

based on achieving a full value of room noise reduction there are a few more things to discuss, which you are aware of like the attic vent..

Are attic vents a significant contributor? I've debated this, and the home has a similar attic setup to this: https://buildingscience.com/documents/published-articles/pa-crash-course-in-roof-venting/view

The problematic room has soffit vents right outside of the window, so that can be a possible transmission path.

[Randy S]

well according to indo, the thickness they use for acoustic windows is 1/4"  and the standard inserts are only 1/8"
unfortunately, when it comes to low frequency you need mass and there are some situations where 3/8" is still not enough.

You are going to need to determine the area of least resistance for sound to penetrate your home...
find out the detail of the soffit build, maybe it does not have insulation and maybe another layer of drywall could be added to improve mass of the soffit.

Randy S.