Sept. 2 Update: NASA issued the following explanation on Monday for the strange noises: "A pulsing sound from a speaker in Boeing’s Starliner spacecraft heard by NASA astronaut Butch Wilmore aboard the International Space Station has stopped. The feedback from the speaker was the result of an audio configuration between the space station and Starliner. The space station audio system is complex, allowing multiple spacecraft and modules to be interconnected, and it is common to experience noise and feedback."