 This complex and unfinished work attracted much interest at the time and was reviewed by philosophers such as Meinong and Natorp and by psychologists such as J. Sully, H. Ebbinghaus, and especially W. Wundt who, in his anonymous review of the first volume of the book, criticized Stumpf’s method and the hypothesis of the relativity of sensations to judgment. (see C. Allesch, 2003) Let us recall, however, that this book is not a phenomenological study of sounds but rather a study pertaining to “judgments about sounds,” and it belongs therefore to the field of psychology in the narrow sense. (Stumpf, 1906a, p. 31) Stumpf makes it clear, however, that the judgment in question is not categorical but it is a judgment of a particular type which he calls apprehension or apperception. Stumpf claims moreover that there are sensory contents which are not related to judgments or any other mental functions such as space as he had demonstrated in his Raumbuch. (see J. Bouveresse, 2006) Two important contributions from Stumpf in this book (Kaiserl-El-Safti, 2011, pp. 38–39) rely on the famous concept of fusion (Verschmelzung) by which he characterizes the phenomenon of consonance, which in turn constitutes the foundation of music, and the theory of relations that Stumpf develops in the first volume of this work. (Stumpf, 1883, § 6) This theory of fusion led to a debate with Brentano (see C. Allesch 2003, R. Martinelli, 2013) and the importance of this notion in Husserl’s phenomenology is well-known, particularly in relation to the latter’s conception of figural moments. (C. Ierna, 2009)