"The Sound of Her Voice" is the 149th episode of the syndicated American science fiction television series Star Trek: Deep Space Nine, the 25th episode of the sixth season. It was first broadcast on June 10, 1998.

Set in the 24th century, the series follows the adventures on Deep Space Nine, a space station located near a stable wormhole between the Alpha and Gamma quadrants of the Milky Way Galaxy. In this episode, the Defiant answers a call for help from a stranded Starfleet officer, while back at the station, Quark attempts to distract Odo so that he can conduct a smuggling operation.

While traveling home from an escort mission, the crew of the USS Defiant receive a distress call from Captain Lisa Cusak (voiced by Debra Wilson), a Starfleet officer stranded on an alien world by herself, after her ship has been destroyed by actively scanning a strange planet. After working a means to communicate with her, they discover that she is stranded on a Class L world with a high concentration of carbon dioxide in the atmosphere that will eventually kill her without regular doses of "triox" medication, which she is running out of. Dr. Bashir (Alexander Siddig) tells her to cut her dose such that she will survive the six days that it will take the Defiant to reach the planet. In turn, Captain Cusak asks that they keep a constant conversation going with her to keep her alert and to make her feel less isolated.

As they travel, each of the crew becomes closer to Captain Cusak as they discuss their own personal problems with her. When Dr. Bashir discovers that Cusak's supply of triox is more critical than they thought, Captain Sisko (Avery Brooks) orders the phaser bank power to be routed to structural stability controls to increase the Defiant's speed. They arrive at the planet shortly after Cusak has fallen unconscious, giving them a limited amount of time to find her. After figuring out how to bypass a strange energy field that surrounds the planet with a shuttlecraft, the crew finds the long-decomposed remains of a woman's body deep in a cave, having been dead for about three years. O'Brien (Colm Meaney) theorizes that the energy field caused their communications to travel through time. Sisko orders them to collect Cusak's body and gives her a proper burial back on Deep Space Nine as a Starfleet officer and trusted friend.

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