Over the past century, scholars have identified examples of liturgical chant belonging to more than one Western liturgical tradition, including Franco-Roman, Old Hispanic, Old Beneventan and Milanese. In a seminal study, Kenneth Levy identified a set of offertories that circulate in the Franco-Roman, Old Hispanic and Milanese traditions, arguing that all existing versions derive from an earlier, Gallican tradition. This article expands the evidence for connections between the Franco-Roman and Old Hispanic traditions, identifying nearly two dozen Franco-Roman responsories that are shared with the Old Hispanic rite and may be of Gallican or Iberian origin. The diversity of their liturgical assignments and circulation patterns suggests that the exchange of repertory took place at different times and through different routes. Many of these responsories are assigned to the later layers of the Roman liturgy. Others were added to the Old Hispanic liturgy between the eighth and tenth centuries.
Just over half of these responsories show enough melodic connections between the Franco-Roman and Old Hispanic versions, in contour and melismatic density, to imply a shared melodic ancestor. Each version, however, uses the formulas associated with its own tradition, indicating that the melodies have been assimilated to the style and formulaic content of the receiving tradition. Despite the resulting melodic differences, we identify certain commonalities between Franco-Roman and Old Hispanic chant, such as text-setting strategies and common cadential contours, that facilitated the exchange of repertory.