What trees can I plant to block road and gate noise?

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

1. 1
   Planting tall cypress trees to act as a visual or sound barrier
2. 2
   Consulting a local plant nursery for shade-tolerant species
3. 3
   Checking zoning and setback rules or permits for neighboring structures
4. 4
   planting trees
5. 5
   putting up a fence
6. 6
   installing a speaker system

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.