261.5 Hz

261.6 Hz is middle C in standard concert tuning. Barbara Hero's isotope frequencies map an element's atomic properties through Pythagorean Lambdoma ratios into the audible range; her table places Uranium-238 (half-life ~4.47 billion years) at this C. Hero used such tones as fundamentals for Lambdoma-matrix compositions. Auriviel anchors tracks at middle C for a familiar, resonant centre — presented as music, not medical treatment. Independent of any tradition, controlled clinical evidence that a specific frequency produces a specific health effect is limited and mixed. Auriviel presents these tunings as music and contemplative practice. This page is for general information and relaxation. Auriviel's frequency music is not medical advice, diagnosis, or treatment, and no health outcome is claimed. If you have a medical concern, please consult a qualified professional.