Bamboo can't block sound, but it does make some "white noise" - rustling leaves and clacking culms in a breeze - that can disguise background noise. The only thing that will block sound is a berm or solid wall.

Narrow planters of bamboo won't likely give you what you want, except for a visual screen. You don't say how big the planters will be, but my guess is that they will not be sizable enough to encourage the kind of bamboo growth that would give you adequate screening or "white noise."

Also, there's no such thing as a bamboo that has minimal leaf drop. They don't shed like deciduous trees, but there will always be old leaves falling and new ones coming in. If you do plant bamboo, you can sweep the path and dump the leaves into the planters as important and crucial mulch for the bamboo.

Hope that helps!

A few years ago I too was in search of a sound barrier. Anything short of a cement wall makes little difference.

However as Cady suggested you might consider creating a preferred sound in order to help drown out the freeway noise. A nice water feature with a small waterfall would be perfect.

Just a thought
Pura Vida

Here is a link that might be useful: Garden Blog with Pictures

Thanks for the prompt replies!

I'm not unrealisticly thinking the sound would be gone. Our developer was just forced to put a (cheap)soundwall in to get the noise to city code. It's helped somewhat, so I know that even walls can't do a whole lot if they aren't tall enough. I'm just hoping to reduce the hollow echoing between our houses, not eliminate the freeway sound. The path between our houses is parallel to the freeway. I think what happens is the sound hits the side of my house, bounces to his, and then goes back and forth. I should have been more clear, but didn't want too long of a post on my first time. I thought perhaps bamboo would filter/absorb at least a little of the reverberating waves as they travelled between houses. I still may be way off in my thinking! My walkway is about 5' wide and 30' long where I was thinking of putting long, narrow planters along the fence. Wouldn't afternoon breezes help with the leaf rusting sound, since the breezes flow along the walkway?

I have some queen palms and am installing a spill fountain in the backyard to help drown out the sound as well. I figure, the more other noises I have, the less freeway noise I will hear. Please don't get me wrong, I LOVE where I live, don't wanna move, just wanna naturally reduce/absorb noise if possible.

As far as the good neighbor/leaf drop question, I would guess some (probably varieties with small, dense vegetation) would leave more leaves for my neighbor (and I) to pick up?

Thanks for the help. I really do appreciate it.

Trouble with leaf drop is, when bamboo is dropping leaves, it's dropping culm sheaths (The wrappers around new shoots)! All bamboo has plenty of leaves, because that's how they make (photosynthesize) food. It's true that some kinds are denser than others and produce more foliage overall, but even the "lighter" types have plenty of leaves.

Again, though, they don't drop lots of them all at once, just a few here, a few there. Get an inexpensive electric leaf blower-vacuum and suck up the leaves once a week or so. It's easy and fast.