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.
Two things more emerge from this short example. First, 'unpitched sound' is not always noise; it can be a musical sound as well. The distinction between music and noise based on the difference between periodic and non-periodic vibrations does not hold. Second, noise seems to be synonymous with undesirable sounds here. When accepted (as music), the same sound is no longer noise. But is it possible to demarcate the border of these undesirable sounds? And can listeners to music, visitors to a concert, banish every undesirable sound? Would a soundproof room with the most advanced audio equipment be an option? Perhaps, we might then be able to avoid undesirable sounds and background noise (unless we are diverted by the sounds of our body during very soft passages). But is it possible to avoid interference in the 'music itself'? Do the sounds of the bellows from an accordion, the breathing of singers, or the sounds of fingers sliding across the frets of a guitar belong to the music or should they be excluded? Indeed, is that at all possible? Some composers think of background noises made by musicians and instruments as an essential part of the composition. What about the humming and panting that is inextricably bound to the performances of such musicians as Glenn Gould, Keith Jarrett and Art Blakey? What about the applause, the enthusiastic hissing and shouting of the audience on live recordings? Stage sounds on live opera recordings? Movie soundtracks that (necessarily) include street sounds and dialogues? And what if background noises are part of the composition as is found in some works of John Cage (cf. Cage and Noise) and Luigi Nono (cf. Silence and/in Music)?
 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.
Is another relationship with noise conceivable? As one of many composers, John Cage has sought to open our ears to 'non-musical' sounds in his compositions. According to Cage, the qualification of sounds as non-musical or noise is not so much related to intrinsic sound properties as it is to our attitude towards sounds that we do not instantly consider to be musical. When we pay attention to sounds that we usually prefer to ignore - the same attention we reserve for musical sounds - we might experience these sounds as far less disturbing. Cage begins his text, The Future of Music: Credo, with: 'Wherever we are, what we hear is mostly noise. When we ignore it, it disturbs us. When we listen to it, we find it fascinating' (Cage, 1961, p.3). The more one realizes that the sounds in our environment are musical, the more music there is. Applied to the musical practice: 'A cough or a baby crying will not ruin a good piece of modern music' (Cage, 1961, p.161). When a sound becomes undesirable because it interrupts or hampers music, we may try to banish it. Cage, however, seems to drive at a change in our attitude towards noise in relation to music. Since it is virtually impossible to filter out each and every noise, why not try to relate to these sounds in another (a more positive?) way?
 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.