Average cochleogram obtained from (a) the styrene-exposed slim (312g) group, (b) the styrene-exposed fat (411g) group. The totality of the animals were 21 weeks old. Styrene exposure : 700 ppm, 6 h/d, 5 d/w, 4 w. Abscissa - upper trace: length (mm) of the entire spiral course of the organ of Corti from the bottom of the hook. - lower trace : frequency-map according to Müller (1991). Ordinate: hair cell loss in percent. IHC: inner hair cells; OHC1: first row of outer hair cells; OHC2: second row; OHC3.