President Donald Trump welcomed Ukrainian President Volodymyr Zelenskyy to the White House for a high-stakes meeting as the U.S. president pushed for a deal to end Moscow's war on its neighbor. A host of European leaders joined the pair.

The magnifier of sound, a descendant of 150-year-old technology, on Monday added to its long history of cutting through the most scripted political spectacles when it captured more than two minutes o...