On the use of averaging for auditory evoked response detection

Quantifies the relationship between the signal-to-noise ratio (SNR) and the number of realisations of the auditory brainstem response. The commonly-held belief that the SNR increases with the number of terms being averaged originates from the assumption that repeated realisations of the evoked potentials are perfectly correlated. We show that, in practice, the correlation is far from perfect, and this dramatically affects the number of observations which are required to obtain the desired SNR. The relationship reduces to the accepted form for perfectly correlated signals.