Mean N1m amplitudes normalized to the amplitude evoked by the signal without masker in three masker intensity conditions.

<p>The upper (a) and lower (b) graphs show the respective values before and after subtracting the masker response. The error bars indicate standard errors.</p

Mean N1m amplitudes evoked by three maskers without signal in three intensity conditions.

<p>The error bars indicate standard errors. Because the N1m amplitudes were normalized to those evoked by the left masker without signal in each intensity condition, the standard errors for the left masker without signal resulted in zero.</p

Schema of the seven stimulus sets.

<p>The presentations in the right (R) and left (L) ears are separately illustrated. The solid and open trapezoids indicate the masker and signal presence, respectively.</p