In Phoenix I see oleander used for noise abatement.

I do have experience being uphill from noise and I don't think anything can be done about that. Of course it depends on how far uphill. The closer the barriers can be to where you want it quieter the better they work.

As Waterbug said, a good dense hedge of oleander should do the trick. Unfortunately, you'll probably need to establish irrigation lines in order to first get the hedge established and later, to get it to grow big.

Your other option is to build a tall block or concrete wall, much like the Dept of Transportation does for residential areas near highways.

:)

it's a nice idea, and the plants may make you feel better, but it doesn't work like that.

the range of human hearing spans wavelengths that are very short (like to block low frequencies, you need material proportionate to the wavelength. so a thick adobe or block wall will help with the "roar" of mids, but the low end will still be there.. fortunately, taking care of the mids will make the sound less wearing (it's mids that the ear is most sensitive to due to speech..)

you want a wall, the thicker the better. pick your plants because they're beautiful or have other qualities, don't chuck in a bunch of oleanders because you heard they'll lower the decibels of traffic.. :)

xoxos, I always wondered why plants had less of an impact on sound than I would have thought.

I have read that trickling water would help with street noise. Like a small fountain nearby.

waterbug_guy - my experience is more with the theoretical field of sound, including practical applications like monitoring environments and simulation. practice is often different, but i'd think.. only to a degree :)

in terms of transmission, then yes, the wavelength is important to baffling. the best pro recording studio insulating job won't block out the lowest frequencies of heavy traffic.

there are some factors that could be pertinent to vegetation - of course, theoretically, any signal added to the opposite of itself is cancelled out, which is how the noise cancellation headphones work. "masking" is when you can't hear a sound because of interference in the same frequency range, eg. running water.

i recently saw some newer research where someone was effectively lowering volume by a significant portion, in a very narrow frequency range -

they constructed baffles of vertical dowels arranged in a 60 degree pattern (eg. triangles, hexagon), maybe three or four rows of these vertical columns.

the principle was that the baffle blocked sound at the frequency corresponding to the distance between the dowels, which is why i mentioned the (+A)-(-A) and masking.. the dispersive reflections of sound in this "forest" of dowels impeded sound from the other side of the screen.

so, a forest of bamboo or oleander would have an effect, but i think it would still have to be a thick stand before and appreciable drop was produced :)