When are landscaped earthen berms used instead of manufactured acoustic walls?

In master-planned community parks, civil engineers prefer constructing earthen berms rather than manufactured sound walls. A 6-to-8 foot high soil berm topped with dense sod completely blocks the direct line-of-sight sound path. Unlike concrete walls, which reflect sound back across the courts, soft grass and soil absorb acoustic energy, eliminating echo reverberation. However, because soil requires a 3:1 slope angle for structural stability, an 8-foot tall berm requires a 48-foot wide base footprint, making it suitable only for expansive suburban parks with generous spatial easements.