In Noise as Undifferentiated Sound, I discuss the idea that there is no stable basis for a distinction between music and noise. That page focuses on the boundary between music and noise for the most part from a physical perspective. Shifting the emphasis to the receiver's side opens a new outlook on this distinction. Noise as Undesirable Sound. No complete overview. No new theory. Just a few rudimentary, rough remarks and questions to open a space in which the relationship between music and noise can be rethought, in which the boundary becomes less distinct, maybe even less relevant. Prolegomena. Four short exploratory reflections which bring us to John Cage whose compositions deconstruct the boundary between noise and music.
 Noise is the negative of musical sound. Noise is an undesirable sound around or during musical performances: the coughing and rustling during a concert, the interference of (antiquated) audio equipment, the scratches on a worn-out LP. Noise interrupts the things we want to hear. We experience sound as noise when it prohibits or hampers our contact with music. Generally, noise is a resonance that interferes with the transmission of a message in the process of emission; it is the term for a signal that disturbs the reception of a message. Sounds are noise when they disturb our concentration (or sleep), when they are physically harmful to us (high sound volume). On a biological or physical level, noise can be a source of pain. In Noise, Jacques Attali enumerates some consequences of excessive sound in the immediate environment: diminished intellectual capacity, accelerated respiration and heartbeat, hypertension, slowed digestion, neurosis, altered diction. The eardrum can be damaged, even destroyed, when the frequency of sound exceeds 20,000 hertz, or when its intensity exceeds 80 decibels (cf. Attali, p.27).
 Noise related to (high) sound volume. On a physical level the idea of undesirable sounds seems clear. Greater problems occur when we move to noise as a contextual phenomenon. Categorizing sound as noise, then, means assigning a status to it that is relative to established norms for permissible and proscribed (musical) sounds. Here, there is no stable basis for noise; it is bound to a context. A sound is experienced as undesirable - i.e., as noise - in a specific context, while the 'same' sound may be accepted as music in a different context. When I hear my neighbor's typewriter while I am listening to a CD of Bach's Cello Suites, I will think of it as disturbing. However, the sounds from the typewriter 'as such' do not have to be the cause of my discomfort. When I listen to Satie's Parade, I appreciate the typewriter sounds as musical sounds; they are part of the composition. Noise exists in relation to the context within which it is inscribed.
 Many re-releases on CD's contain the following 'warning': 'The music on this Compact Disc was originally recorded on analog equipment, prior to modern noise reduction techniques. This Compact Disc preserves, as closely as possible, the sound of the original recording, but its high resolution also reveals limitations in the master tape, including noise and other distortions'. A standard phrase, perhaps illustrative of our current-day appreciation of sounds. Refinement of hi-fi equipment and recording techniques leads to a 'new' aesthetics that aims at the exclusion of errors, hesitations and other unwanted sounds. (The whole of these unwanted sounds could be summarized under the common denominator 'noise'.) Or, as Jacques Attali puts it: 'The absence of noise has become a criterion for enjoyment' (Attali, p.124).
 The world has unmistakably become louder since the Industrial Revolution. Our ears are exposed to a greater intensity of decibels. More noise on a physical level. However, a parallel development takes place concurrently: a 'musicalization of culture' as George Steiner calls it in his book In Bluebeard's Castle. The development of audio equipment and all kinds of reproduction methods has enabled us to avoid every undesired sound by covering it with a layer of music. (Or could this music in turn be experienced as undesirable sound?) No doubt, this musicalization, this omnipresence of music in our society, has its positive sides. Music at work, reportedly, even leads to an increase of economic productivity. I want briefly pay attention to two other consequences of this musicalization of culture. On one hand, many people have come to fear silence: even the supposed absence of sound is disturbing and needs to be suppressed under a carpet of sound. On the other hand, the omnipresence of music has markedly reduced our tolerance towards 'other' sounds, towards noise.
 Four brief thoughts on noise as undesirable sound. Four thoughts ending with a rethinking (maybe even a disruption) by John Cage - a rethinking or disruption he mainly articulates in music - of the boundary between music and noise. In Cage and Noise, I enter at length into a possible deconstruction of the boundary between music and noise in Cage's compositions.