ruído cinza, silêncio cinza

ruído cinza, silêncio cinza (grey noise, grey silence) is an octophonic piece comprising eigth posters in distinct colors, to be affixed in urban environment (preferably on public lighting posts close to each other or on opposite sides of the same road, suggesting a possible ways among them). Seven of these poster have the word "ruído" (noise in Portuguese) written in small case. The eighth of them bears the word “SILÊNCIO” in upper case. Text is always in grey color. Names of colors that fill the posters are commonly used in the audio jargon to describe different kinds of noise, establishing analogies between the frequency distribution with the color spectrum present in visible light.

Colored noise

White noise contains an estatstical distribution of all frequencies audible to human beings sounding with the same energy (as white light which contains the sum of all visible colors). Pink noise has less energy towards higher frequency and more towards the low end, being the intensity of each frequency (f) proportional to 1/f (as red is the color with the lowest frequency range, this kind of noise is called pink, as if it were a mixture of white and red). There is also red noise, even more emphatic towards low frequencies (intensity proportional to 1/f²), which is imprecisely also called brown noise, for it's frequencies may be generated by Brownian motion, named after botanist Robert Brown who observed it for the first time in 1827.

Blue noise can be obtained as the frequency distribution curve in pink noise is inverted. Violet noise comes by the same procedure applied to red/brown noise. Black noise has a somewhat controversial technical meaning, which may refer to the total absence of frequencies (silence), when thought in opposition to white noise.

Last, grey noise is a randomly generated noise attenuated by a specific curve that follows the sensibility of human hearing (bigger in some frequency and smaller in others), as a way to guarantee that every frequency is perceived with equal loudness. This emphasis on perceived loudness points out to a diversity of possible grey noises, as different listening conditions and even individual characteristics of each ear may interfere in these perceived equilibrium of intensities. Though grey noise has its nuances determined by a listening condition wich is specific, localized and individual.

The grey city

In the urban context of São Paulo, the grey colour recently acquired a specially dramatic tone, being used to cover large amounts of urban art, taken by the municipality as unwanted noise to be silenced to "beautify" the city. Grey, noise and silence are elements that this intervention aims to somehow bring into sounding.

Places chosen for the two interventions done so far stage urban space disputes which have sound as a privileged element. The Franklin Delano Roosevelt Square, the same theaters which triggered a regional revitalization were not so much time ago were fined for breaking the city noise regulation. The second one, Luz, has a place devoted to music, known as Sala São Paulo, which constitutes a strategic placeholder for an enormous real estate speculation process that has begun in that neighbourhood in the 1990's and is recently speeding up.