Patent ID: 6876828

Claim:
A method of image formation comprising: forming an image on a recording medium so that a discomfort index S of sound obtained by the following tone quality evaluation equation (a) expressed in a regression equation, using regression coefficients of loudness value, sharpness value, tonality value, and impulsiveness value of psychoacoustic parameters obtained from an operating noise at a position away from an end face of an image formation apparatus by a predetermined distance: S=A ×(loudness value)+ B ×(sharpness value)+ C ×(tonality value)+ D ×(impulsiveness value)+ E, where 0.209≦A≦0.249 0.308≦B≦0.439 3.669≦C≦4.984 0.994≦D≦1.461 −4.280 ≦E ≦−3.274 (a) satisfies the condition of: S ≦0.6708×Ln (ppm)−2.824 16≦ppm≦70, and where ppm is defined as the number of sheets of A4 lateral size paper printed in one minute, and Ln is natural logarithm.