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[nate-b]

I am posting with a request for different information from what I have seen in similar posts.  If anyone has seen something applicable, please link to the thread.

Problem: I live in the tropics and I want airflow while blocking the noise of traffic and party-goers (the bar in our building closes at 5 am and for 30 minutes it pretty loud).

Proposed solution:
Hang a flat board as a baffle from the curtain rod in front of the open window.
The baffle wouldn't touch the window, so air could flow through.
The baffle is around 4inches (10cm) bigger along all edges of the window.
On the side of the baffle facing the street I would put a reproduction of a sound-absorption solution that I saw in a university classroom.

The sound-absorption solution that I saw 1 eliminated reflection of sounds in the talking range (say 300-3400).
It was made of 2-inch (5-cm) half-pipes of perforated steel, placed vertically, side by side, so the inside of the pipe was visible.
I don't understand why the half-pipes were perforated with 1-mm holes in a diamond grid every 1 cm or so.
The solution eliminated reflections uncannily well.  When I put one ear to it, I heard the teacher from one side but had the feeling of being on the edge of emptiness on the other.

So I figure hanging a baffle like this should keep the sound from coming in.

I can also hang one on the outside of the window (where there is a balcony facing in).  Any sound would have to bounce back and forth between the two sound-absorbent surfaces before coming into the room.

The original design was in steel.  I might opt for plastic to save money.  If I can find it, I would make the whole thing out of transparent materials, to allow light through.

So, I suppose some people will say that I'm unrealistic.  But does anyone see any hope in this design?  Any suggestions?

Any help would be appreciated.

[Randy S]

Your design sounds plausible, holes in the half pipe fall under the helmholtz resonator, similar to a car muffler.
It would all come down to what amount of reduction you achieve.

If you do not achieve enough reduction you would have to go back to the baffle box design making series of 90* turns at the opening.

Bar noise is very difficult to reduce with out major soundproofing.

Let me know how your plan works I would like to hear the results.

Randy S.