440 Hz vs 432 Hz: should you tune to concert pitch or scientific pitch?

How they differ

Before the 20th century, there was no single tuning standard. Regional pitch varied from around 415 Hz (Baroque) up to 456 Hz (some military bands). The 440 Hz standard emerged in the early 1900s as a compromise that suited most instruments and voices, and was codified by ISO in 1955. The 432 Hz alternative, sometimes called Verdi tuning because the composer advocated for it, sits at a mathematically cleaner C = 256 Hz (a power of 2) below it. Proponents of 432 Hz argue it sounds warmer, more relaxing, or resonates with the natural world. The scientific evidence for those claims is thin to nonexistent, but the alternative pitch has a real following in meditation, ambient, and new-age music communities. What's objectively true is that 432 Hz is 8 Hz lower, which makes any piece transposed to it slightly warmer and lower in pitch - a difference most listeners register subconsciously.

Verdict

Use 440 Hz for any context where you need to play with other musicians, match sheet music, or work with the broader musical world. Use 432 Hz for solo ambient, meditation, or new-age work where the slightly lower pitch is part of the aesthetic you're creating. The two are not objectively better or worse - one is a 1955 standard, the other is a cultural choice.