Ernst Chladni at the understanding of electron orbitals. Since at least 1738, a musical instrument called a "Glasspiel" or "verrillon", created by filling beer glasses with varying amounts of water, was popular in Europe. The beer glasses were struck by wooden mallets shaped like spoons to produce "church and other solemn music". Benjamin Franklin was sufficiently impressed by a verrillon performance on a visit to London in 1757 that he created his own instrument, the glass armonica, in 1762. Franklin's armonica inspired several other instruments, including two created by Chladni. In 1791, Chladni invented the musical instrument called the "euphon" (not to
Glass harmonica and locate ranges of sounds. Above 4 kHz people primarily use the "loudness" of the sound to differentiate between left and right ears and thus triangulate, or locate the source. Below 1 kHz, they use the "phase differences" of sound waves arriving at their left and right ears to identify location. The predominant pitch of the armonica is in the range of 1–4 kHz, which coincides with the sound range where the brain is "not quite sure", and thus listeners have difficulty locating it in space (where it comes from), and discerning the source of the sound (the materials and