Pierre Boulez frequently describes form in his own compositions using terminology borrowed from acoustics, specifically the term envelope to describe the “long trajectory of the music”. In this paper I appropriate Boulez’s idea of envelope-form to analyze aspects of timbral morphology in the Abschied movement of Gustav Mahler’s Das Lied von Der Erde. To this end I consider Boulez’s own recording of the movement with the Vienna Philharmonic in order to show, by extension, how his compositional concepts of form might be applied to his interpretative shaping of musical forces as a conductor. My analysis focuses on “noise” both as an acoustic and semantic concept. I begin with Mahler/Boulez’s use of attack noise in the harp, oboe, mandolin, and voice in relation to the expansion of musical space. Next, I consider the complex spectrum of the tam-tam, its non-harmonic bands of noise and the metrically irregular pulsing of its acoustic beats, followed by a brief section on envelope decay and Mahler’s cello writing. I conclude by showing how all of the above fit with an expanded use of the term “noise” borrowed from information theory, where it refers to the unwanted accumulation of data into a semantic communication (“unwanted” insofar as it is received but not sent, that is, not sent as part of the original message from informer to informee). This “unwanted”/“unforeseen” characteristic not only invokes Adorno’s notion of “Otherness” in Mahler’s music, but I believe also manifests as an inherent aspect of performance decisions and the perception thereof.
 Violeta Urmana, mezzo soprano; Deutsche Grammophon (289-469-2), 2001.
 To assist in the methodological process of analysis, spectrographs are used to help outline the timbral progressions (spectrographic images allow one to discuss in detail elements of the acoustic spectrum including overtones, non-harmonic bands of noise, formants, and changes of intensity).