Description:
<p> The sign ϕ has both mensural and non-mensural meanings in the works of Du Fay. As a mensural sign, ϕ almost always represents a mensura on the perfect breve, which may or may not be equated proportionally with a perfect semibreve of major prolation. In one instance, it represents a mensura on the imperfect breve, which is equated proportionally with an imperfect semibreve of perfect tempus. Mensura is only loosely related to tempo. When ϕ represents a perfect breve mensura in non-simultaneous contexts, it does not specify a fixed tempo relation with uncut signs, even in works that scholars have classified as 'isorhythmic'. Mensura is, however, intimately related to the sense of musical pulse, which governs many aspects of compositional structure. The choice of mensura in performance has a significant impact on the way rhythms are felt by performers and perceived by listeners. Mensural and non-mensural uses of ϕ in Du Fay's works can be distinguished with reasonable certainty on the basis of musical style and genre. </p>