cool the feet.... want to hear the sound of water running to muzzle street noise? I have two suggestions. One, add a water feature to your small yard or townhouse garden then get a birdcage with a couple of singing birds.... The impact will be such that you'll want to spend the entire summer outside.
As long as a pot can hold water it can be used for a water feature.
Add a small bird bath as your water feature in a very small garden.
This well designed garden can be scaled for a smaller spacer too.
Sometimes all you may have to work with is a corner. I love the way this garden also uses plantings in pots to add variety to the foliage surrounding the water feature.
Here is another example of a water feature that can be scaled for a smaller space.