1. A voice retrieval apparatus comprising: a display; a memory; and a processor that executes the following processes: a voice recording process of storing recorded voices in the memory; an accepting process of accepting a retrieval term; a retrieval process of retrieving, from the recorded voices, a plurality of candidate segments where an utterance of the accepted retrieval term is estimated; a first display control process of displaying a plurality of pieces of candidate identifying information respectively corresponding to the plurality of pieces of candidate segments on the display in an order of likelihood; a first replay process of replaying voices in a candidate segment corresponding to a piece of candidate identifying information that is identified in accordance with a first user operation by which the piece of candidate identifying information is defined from the plurality of the pieces of candidate identifying information; a user operation accepting process of accepting a second user operation by which a piece of candidate identifying information is identified from the plurality of the pieces of candidate identifying information after the voices in the candidate segment are replayed; and a second display control process of adding a marking to a portion of display information indicating a time transition of the recorded voices, the portion of the display information corresponding to the piece of the candidate identifying information identified by the second user operation, and displaying the display information with the marking on the display, in accordance with a third user operation.
6. The voice retrieval apparatus according to claim 1 wherein: the processor replays voices in each of two or more candidate segments different from one another in accordance with the first user operation in the first replay process, the two or more candidate segments corresponding to two or more pieces of candidate identifying information that are different from one another and that are identified from a plurality of pieces of candidate identifying information by the first user operation; the processor accepts the identification of the two or more pieces of candidate identifying information identified from the plurality of the pieces of candidate identifying information through the second user operation after replaying the voices in each of the two or more candidate segments, in the user operation accepting process; and the processor adds two or more markings to two or more portions of the display information that correspond to the two or more pieces of candidate identifying information identified by the second user operation and displays the display information with the two or more markings on the display in accordance with the third user operation, in the second display control process.