Sahasrara and the Modern Correspondence

Sahasrara, the Crown chakra, is described in the classical Sanskrit sources through its own extensive symbolism, most famously as a thousand petalled lotus, with no reference to Western musical pitch. Its pairing with the note B in the modern chakra-tone system completes the ascending mapping used throughout these entries, the seventh and final scale degree matched to the seventh and topmost chakra, a construction of twentieth century Theosophical and later New Age writing rather than an element of the older tradition.

B's position as the seventh degree of the C major scale, the leading tone that sits a single semitone below the octave and creates a strong pull of resolution back up to C, is sometimes read by contemporary esoteric writers as fitting for a chakra associated with transcendence and completion, the note itself seeming to reach upward toward the octave the way Sahasrara is described as opening toward states beyond the embodied self; this is, again, an interpretive reading added after the correspondence was already fixed rather than the reasoning behind its original construction.

Sources The Serpent PowerSir John Woodroffe (Arthur Avalon) with Rainbow Body: A History of the Western Chakra System from Blavatsky to BrennanKurt Leland