It explained the mystery noise as feedback from the speaker that was the result of an audio configuration between the spacecraft and the ISS. Wilmore reported the sound as he was working inside Starliner on Saturday.
"The space station audio system is complex, allowing multiple spacecraft and modules to be interconnected, and it is common to experience noise and feedback," NASA stated. "The crew is asked to contact
mission control when they hear sounds originating in the comm system."
NASA also took the opportunity to state the feedback has "no technical impact to the crew, Starliner, or station operations, including Starliner's uncrewed undocking from the station no earlier than Friday, Sept. 6."