If your primary purpose is to reduce noise, then I think you are going to be disappointed. Plants have very little ability to deflect noise, even if very thickly planted. The only effective noise barrier is a solid wall and of pretty good height as well. You might want to consider some sort of noise distraction - a fountain or other water feature, plants like bamboo that will create their own sound when the breeze blows, etc. This topic comes up from time to time on the Landscape Design forum. You may want to check there for previous posts discussing this issue. Not sure what shrubs may work best as hedges for your location - Australian plants are not all that adaptable to much of the US :-). Have you posted this in the Australia forums? Here is a link that might be useful: GardenWeb Australia

Uhhh - I don't wish to sound rude, but what do you think will solve your problem, that won't involve a little effort....or expense? Cities spend millions every year on noise mitigation. What you COULD try that may not involve too much, is writing to your Congressperson/local member etc and see if they will bring some pressure to bear to construct noise mitigation barriers - I used to live in Sydney, Australia, and with the construction of newer freeways they constructed a lot of acoustic barriers - after a while, they started to appear along the old freeways too, where people had suffered the noise for decades. Either the roads people realised there was a certain inequity there, or the people began asking why they weren't afforded the same courtesy. I actually think your friends' suggestions are good ones, although tree plantings would have to be very, very dense to reduce the noise - but visually and air quality wise, they'll help a lot. Trees are very good air cleaners. I don't know if it's too warm in San Diego, but people here in Central BC use decorative cedars a lot for privacy fencing = they grow tall and thick, and quickly. I think the idea of a fountain's actually a really good idea - if it's a noisy one, the generation of 'white noise' will actually mask quite a lot. You might also consider wind chimes, kinetic sculptures and the like, but otherwise, there's not a lot you can do. I suppose if regulations permit, you could build your own acoustic fence but that wouldn't come cheap, and won't be very effective unless you do it down your neighbours sides as well - not practical - or all of your neighbours do the same, so it goes some distance. Sound doesn't just travel in straight lines. You haven't mentioned the noise in your house, so I guess your glazing and insulation's pretty good - so you're lucky in that regard. There are such things as active noise cancellation devices, but I imagine they're not cheap. Cheaper, though, would be noise cancellation headphones, which I think you can wear just to mask the noise (they generate sound waves to counter noise, and are insulated) or you can listen to music AND cancel out noise.

How are they planning to mount the laminated glass in the opening? From what I read it will be a more or less permanent mount? One potential advantage (but also potential acoustical disadvantage) of the plastic insert is that it's much lighter than the laminated glass so it can be relatively easy to remove from the opening if necessary, whereas the laminated glass is going to be heavy. A laminated insert using 3mm glass for both lites will be over 50lbs at the size window that you describe, and while laminated glass can be very safe when handling, it's still a chore if you have to remove it from the opening for any reason. But acoustically that weight (density) is to your advantage. The .06 acoustical laminate glass means that they are using a 1.52mm thick PVB interlayer in the laminated glass. Generically .030" or .76mm interlayer is considered safety, .060" or 1.52mm is considered security, and .090" or 2.28mm is considered to be impact resistant, or the thickness generally used for hurricane impact glass. Adding additional thickness also adds some acoustical advantage as well, roughly 1 to 2 dB advantage for every additional .76mm thickness. I would suggest that if you are going to be looking at comparing laminated glass to acrylic, you might consider using the laminated glass in your bedroom.

Actually, I have a ton of trees all around and behind my house. We lost two large pines to a tornado a couple of months ago so I got my veterinarian who has a landscaping biz to plant these things called "thuja green giant" trees. They are really very lovely (and expensive) but post virtual tour. The couple who looked on Tuesday said the house was "dated" By the way no comments about the interstate and it was rush hour when they were here. Agent has done a ton of marketing to other agents, I too have business cards, laminated with a picture of my house and he even laminated the multi color flyers which remind me of a sales flyer for a World Wide Wrestling match - very coloful, only slightly tacky with colorful boxes and pictures oh yeah, and folks can pick up their very own CD with the visual tour on it when they come in the house. I don't understand "dated" - that one always mystifies me. I am usually much more specific to my agent. Like there is no off street parking and it's in Maine for gosh sakes! The snow plow will cover up my husband's Mini he'll never find it until the snow melts. Of course you should see the fixer upper - and I use that term very loosely - that I was smitten with in Maine. Now it's my husband's turn to compromise. Oh, and it's not near an interstate.