Depends on the medium but if painting, this technique is known as Impasto, layering paint thickly on the canvas making the strokes of the brush or knife visible. When dried the paint appears to be coming out of the canvas creating a three dimensional effect and providing texture. one notable artist that used impasto for its more expressive qualities is Vincent van gogh.
The answer is; because the tone's original decay has become, and vice versa.
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The first musical instrument used by prehistoric men and women to re-create sounds of nature is the human voice.
