2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/16994A review is given of the phonon anomalies, which have been termed ``waterfalls,'' that were recently discovered through a series of neutron inelastic scattering measurements on the lead-oxide relaxor systems PZN-xPT, PMN, and PZN. We discuss a simple coupled-mode model that has been used successfully to describe the basic features of the waterfall, and which relates this unusual feature to the presence of polar micro-regions.5 pages, 8 figures (one color). Submitted to the J. Phys. Soc. Jpn as part of the ASR-2000 Conference Proceedings. Uses asr2k.sty file (which is included)Materials Sciencetext