While a large bamboo grove will provide good visual privacy, you will be disappointed if you expect it to make any significant reduction in freeway noise. I've been growing bamboo for years -- over 70 kinds -- and I am quite familiar with its properties. I'm sorry, but no matter what type or size of bamboo you plant it will simply not be able to significantly attenuate freeway noise. In addition, even though bamboo is relatively fast growing after being planted for several years, you would need to spend tens of thousands of dollars right now to get enough plants to establish a fairly dense grove in say 10-15 years. I'm sure it sounded like a good plan, but I just don't think it will do what you want. I know there are people who will disagree with me, but, during the time I have been growing bamboo and bamboo hedges, I have lived along a busy street and near a freeway: the bamboo did not do anything to make me forget about the traffic noise. I'm not saying it might not have some slight effect, but the time, money, and trouble it would take to grow such a grove is way out of proportion to any benefit you might derive.

Thank you for you honest feedback kudzu9. I was really hoping not to hear this, but it is understandable.

My thought process on starting this project is because when traveling for business I've see many homes in Southern California use them to block the street and such. I was thinking maybe they were more than just blocking visibility and also blocking some sound.

Guess I'll starting looking for other natural/plant ideas. Can't really build a physical wall because it would be just too out of place, and bit impractical, for where I live.

I felt bad to be discouraging, but I thought you'd rather hear that than put a huge amount of effort and money in and then be disappointed. I'm not sure any planted barrier will give you the sound decrease you would like. I live 1/2 mile from a freeway, and the sound travels through a thick stand of trees and bamboo that sit between me and the freeway, especially on rainy days when the tires make more noise. Even solid walls, which I know you don't want to do, have limitations when it comes to freeway noise.

A screen of golden grove bamboo could provide visual privacy. Plant some Norway spruce too. Add a water feature to create sound. For sound the best thing you can do is insulate your house. Use triple pane windows, acoustic wall panels, and ceiling panels,

I've always liked pine/fir/junipter for noise reduction. But yes, not a huge difference and it still takes years. I would say they change the sound of the noise, a softer muffled sound, not really a reduction.

Not being able to see the traffic though is even more important to me. I've always gotten used to the sound, seemed more like a rushing river. But seeing cars/trucks zooming by is not something I think I would like. Out of sight, out of mind. 14 years 50 yards from 880 in San Jose.

One trick I do to cheat the time is to plant way closer together than needed. Then cut down trees to thin as needed. For sound reduction I'd keep the thick branches near the ground so no pruning. And cut trees before lower branches get too much shade and die back.

My experience with how fast bamboo grows and sound blocking is the same as kudzu9.

I had to keep searching but seems the Federal Government isn't all bad. I found the following statement on the Federal Highway Administration web site regarding use of vegetation as nose reduction.

Appears they already know that any amount isn't really going to reduce the noise. Only thing I would accomplish is to cover up the site of traffic as waterbug_guy suggests.

[quote]
Can Trees Be Planted to Act as Noise Barriers?

Vegetation, if it is high enough, wide enough, and dense enough that it cannot be seen over or through, can decrease highway traffic noise. A wide strip of trees with very thick undergrowth can lower noise levels. 30 meters of dense vegetation can reduce noise by five decibels. However, it is not feasible to plant enough trees and other vegetation along a highway to achieve such a reduction. Trees and other vegetation can be planted for psychological relief but not to physically lessen noise levels.
[quote]

Here is a link that might be useful: Highway Traffic Noise

5 decibels is not a huge reduction, unfortunately.

tcameronk-
You're entitled to your opinion, but I still think that bamboo barriers in even more temperate climates will take years to grow and will not produce a huge reduction in sound. Also, being in Zone 5B means the OP will lose most of the foliage and probably many of the culms each winter. I just don't think bamboo is a realistic solution.