Like distinctive features, elements identify natural classes and model the structure of segments. But unlike features, they combine asymmetrically in expressions, with head-dependent relations between elements making a significant contribution to the expressive power of representations. Most versions of Element Theory follow the general principle that a structural domain—such as a segmental expression—can have just one head element. In Backley (2011), however, element structures are permitted to have two heads. Multiple headedness is a consequence of allowing dual interpretation, where each element has two different phonetic realisations depending on its head or non-head status. While dual interpretation is better equipped to capture natural classes and explain phonological processes, its by-product is the need for double-headed expressions, which present a challenge to element-based theory. It is proposed that the six elements (|I|, |U|, |A|, |H|, |L|, |ʔ|) naturally form three pairs of opposing (dark vs light) values, each pair being associated with one of three fundamentals of spoken language: colour, resonance, frequency. It is then argued that headedness relations refer separately to each fundamental property. So, if there are three fundamentals in a melodic structure, then there is the potential for up to three heads in any one expression. The implications of this approach are considered with regard to segmental markedness and language typology.