Recent discoveries in genetic studies require a revision of the fugal structure in ‘Sirens.’ We hope we can shed light on some of the remaining unsolved questions by applying these studies to an interdisciplinary approach. We will put forward our point of view on the most controversial debate on music in Joyce: does this episode of Ulysses contain the eight parts of a fuga per canonem, as the author asserted, and how can we find these parts. Our study is based on the The Sirens Copybook manuscript authenticated by Michael Groden, as well as on the further analysis by two scholars, Daniel Ferrer and Susan Brown. We believe that the role of the character Blazes Boylan in ‘Sirens’ is crucial to divide the episode in eight parts chronologically. First of all, we must point out that some of the concepts that are being used for this interdisciplinary analysis are not unambiguous and depend on the field of study alluded to. A good example is the notion of “theme,” which appears in literature as the main subject of a text, but in music it is understood as a synonym for motif, the musical material that provides a work with its own identity. Some problems of interpretation arise when this term is applied in both music and literature without a clear distinction, such as in the discussion of the eight fugal parts in ‘Sirens.’ Two authors – Stuart Gilbert and Susan Brown – claim to identify these eight sections by mentioning the “themes.” Also, the accuracy of an interdisciplinary study depends on the meticulous use of homogenous sources for the musical concepts. If not, one may argue that the scholar quotes one dictionary or another depending on his/her own interests. Susan Brown recently established that Joyce’s musical knowledge was based on the Grove’s Dictionary of Music (in this paper we will be using the abbreviation GDM). Despite detractors of Brown’s thesis, like Michelle Witen, we believe that for all practical purposes this encyclopaedia is the most useful source for establishing a standardised musical terminology. Every definition of a musical term for this research has been taken from this source