Auditory evoked potentials (AEPs) express the development of mature synaptic connections in the upper neocortical laminae known to occur between 4 and 15 years of age. AEPs evoked by piano, violin, and pure tones were measured twice in a group of 4- to 5-year-old children enrolled in Suzuki music lessons and in non-musician controls. P1 was larger in the Suzuki pupils for all tones whereas P2 was enhanced specifically for the instrument of practice (piano or violin). AEPs observed for the instrument of practice were comparable to those of non-musician children about 3 years older in chronological age. The findings set into relief a general process by which the neocortical synaptic matrix is shaped by an accumulation of specific auditory experiences.