Application of finite impulse response digital filters to auditory brain-stem evoked potentials.

Finite impulse response digital filtering is a linear non-distorting operation and hence can be used to differentiate ABEP components. Since the power spectrum of the ABEP indicates that it contains more than two frequency bands, they can be distinguished by applying digital filters with special characteristics: up to 200 Hz (slow components), 200-400 Hz (medium components) and above 500 Hz (fast components). The results, using these filters, indicate a different nature of components II and IV as compared to I, III and V. While II and IV are not detected under 500 Hz and thus are called 'fast components,' I, III and V are the 'middle components' and appear above 200 Hz. The slow filter results in a 'pedestal' whose peak coincides with peak V. The results of this study show that the ABEP wave form is obtained by the superposition of at least 3 major waves having distinct frequency bands.