Narumi Inada's Chladni Screen simulates Chladni figures on screen and drives them from real-time audio, so singing or playing into the device changes the pattern. It runs on iPhone, iPad, Mac and Apple Vision, and is currently at version 2.2, dated 8 August 2025, with a colour-invert mode added recently. It costs £1.99.
The store listing frames the history correctly, crediting Robert Hooke's 1680 observation and Ernst Chladni's later work in 1787. That is a better provenance note than most cymatics apps manage.
Expectations should be modest. It holds a 3.8 average from ten ratings, and the reviews split between people who like the square-plate mode and people who find it thin or hit technical problems. For two pounds it is a reasonable way to get a responsive plate on a phone when you cannot carry a real one.