Dichotic Listening is a procedure commonly used for investigating selective attention in the auditory domain. Two messages are presented to both the left and right ears (one message to each ear), normally using a set of headphones. Normally, participants are asked to pay attention to either one, or both (divided attention condition) of the messages and may later be asked about the content of both. In a selective attention task, the participant may be asked to repeat out-loud the content of the attended message; a process known as shadowing.