Table 1.

Percentage of the P23H-1 rats classified into the three hearing levels based on their response to natural sounds at different ages.

Age	P20–P60	P90–P110	≥P160
Level I	74.1	44.5	27.5
Level II	14.8	40.7	27.5
Level III	11.1	14.8	45
	n = 54	n = 54	n = 40

Level I, considered “normal hearing” (response to the KS and SC sounds); Level II, a response only to the KS; Level III, considered deaf (no response to either stimuli); n, number of animals analyzed.