An icebreaker
440 Hz became the international tuning standard in 1955 after decades of drift toward it, not from any special formula. A small study using music tuned to 432 Hz found modest heart-rate changes, but no controlled research shows either number 'heals' anything.
In the 1880s he argued for a lower concert pitch than the rising standard of his day, to spare singers' voices; advocates of 432 Hz now cite him and call their preferred pitch 'Verdi tuning.'
In 1834 he presented pitch measurements from a device he built, called a tonometer, recommending 440 Hz to a meeting of German scientists. It was one recommendation among several competing standards used across nineteenth-century Europe.
In a 2026 article she found little scientific support for any special wellbeing effect of 432 Hz, noting the main study was small and non-randomised, and argued that music's effects depend more on how a listener perceives it than on any single frequency.