The reporter's track, also known as a voice-over, is an audio-only track to help advance a news package's story. It is intended to play under the b-roll footage. Typically, the b-roll footage shown on-screen closely matches what the reporter is saying, enhancing the overall story for the viewer.
The reporter writes and records this track, usually after interview sound bites have been selected. The goal of this audio track is to help advance the story by setting up the sound bites and clarifying and summarizing relevant information.