Ask Mr. Smarty Plants

Here is our previous answer to which you are referring. We are trying to think why we even mentioned Gordonia lasianthus (Gordonia), it is not native to Texas at all. In fact, here are comments on its growing conditions:
"Though usually seen in wetlands, Loblolly Bay is tolerant of dry, sandy soil, in which it grows in the wild as a large shrub. It does not tolerate drought. The plant can be finicky and short-lived under cultivation unless its natural habitat is closely matched. Root rot can be a problem when young."

Doesn't sound much like Austin, does it?

Here is another previous Mr. Smarty Plants answer on noise reduction, also from Austin, but it focuses mostly on conifers. Yet another previous answer has more suggestions. Not all of these are evergreen and we feel that a plant with leaves on it all year long will do a better job of muffling noise. We have confined our search to shrubs; they usually are faster-growing than trees, the leaves will tend to be at ear-level, and blooms will be visible. Our three evergreen shrubs suggestions are:

Ilex vomitoria (Yaupon)

Morella cerifera (Wax myrtle) - generally grows better slightly east of here, but if watered, will do well here

Sophora secundiflora (Texas mountain laurel)

Your job is to follow each plant link to our webpage on that plant, not only these but those in the links to previous answers, to find out if your space has the appropriate growing conditions, especially the amount of sunlight, soils and so forth. You can make a continuous hedge of the one you like best, but we prefer mixed hedges with different textures, leaf sizes, and bloom colors and times. Nothing will totally shut out noise, but it will distract you from the noise and birds will visit for berries or shelter.