Listeners responded to two simultaneous messages through dichotic headset circuits. Each message consisted of word groupings from the multiple‐choice intelligibility tests. The signal level of one of the messages remained constant while the level of the contralateral message was attenuated in five steps of three decibels each step. The variable under study was the effect of these attenuation levels upon the reception of the two messages. The simultaneous messages were received under conditions of noise and quiet. The findings were that the general effect of attenuating one of the simultaneous messages was that of decreasing the reception scores of the attenuated message and increasing the reception of the unattenuated message. The effect was more pronounced in noise than in quiet.