A comparison of efferent suppression of compound action potentials by simultaneous and non-simultaneous contralateral noise paradigms

The intent of this study was to compare the effectiveness of continuous ver sus gated contralateral noise in producing efferent suppression of CAPs in guinea pigs. The average contralateral suppression was 2.0 dB when using ga ted noise, with ipsilateral tone-pip rates of 2 s(-1), and 1.4 dB when usin g continuous noise at an ipsilateral tone-pip rate of 31 s(-1). When the ip silateral tone-pip rate employed in the simultaneous paradigm with continuo us noise was reduced to 2 s(-1), a rate equivalent to that employed in the non-simultaneous paradigm, the average attenuation was 2.1 dB, a magnitude comparable to the suppression achieved using gated noise. The present data suggest that, when equated for ipsilateral tone-pip pulse rate, simultaneou s and non-simultaneous contralateral masking paradigms produce comparable l evels of efferent suppression.