I believe that I’ve been able to solve and reproduce the “strange sonar sounds” coming from the Starliner spacecraft.

It sounds like atypical audio feedback with the 2 x 500ms roundtrip ping delay from ISS to NASA.

My comment in the original thread had 400 upvotes before the post was deleted by the mods: https://www.reddit.com/r/space/comments/1f6f4kf/starliner_crew_reports_hearing_strange_sonar_like/ll06sk7/

I've actually heard feedback sound like this in very specific circumstances, such as in an extremely quiet environment with a huge ping delay in a very slow internet setup.

For example, if you put a microphone and a speaker on opposite sides of a very quiet warehouse, and then transmitted the audio with a 500ms delay, it would end up sounding just like this.

Here is a link to my video, which is my crude attempt at a reproduction of them using audio feedback from my wifi door camera, which has about half the ping delay. (It's a higher pitched sound, possibly due to the tiny size of the speaker in the doorbell, and a lot less consistent, but you get the general idea):
https://www.reddit.com/r/SpaceVideos/comments/1f6w4fp/i_believe_that_ive_been_able_to_solve_the_strange/

There is a 500 milliseconds return ping between earth and ISS, which happens to be half the roundtrip delay between these pulses that we're hearing.

And it would have to be in a very quiet room to avoid additional sounds "blowing out" the feedback sound into a high-pitched screech that feedback normally sounds like.

So it is likely that in some totally quiet, closed room at NASA a microphone is open, and transmitting sound to the starliner speakers, and across the room from that microphone at NASA is a large speaker, playing the sound coming down from starliner with a huge delay.

Which means that in a room in NASA they should be hearing the exact same sounds as Starliner.

normally we're used to audio feedback being a rapidly increasing volume screech, but there is a small volume range when the sounds are very quiet and barely able to generate feedback when it sounds like this, and doesn't get any louder. Especially when there's a half second delay.

I'm confident that the press release will say "it was a microphone left open transmitting sound to the module" , or something like that.

Of course, the microphone can't be inside the craft because it would pick up other sounds and cause a feedback runaway that would be much louder and higher pitched.

Why does the sound have a hollow, trailing off kind of "echo" sound to it? That's the echoes in the room at NASA being recorded over and over again into the feedback loop.

if left for long enough, you would expect those echoes to increase gradually every minute, until eventually the sound becomes a continuous feedback whine.

In the 60s, many shows generated sci-fi sound effects in a very similar way – using analogue audio feedback and large delays, which is why this sound has such a "sci-fi" vibe about it.

I expect that when somebody at nasa walks into the room and makes a loud noise, it will cause piercing feedback noise for them and in the starliner module.

Edit
This fellow agrees with me:
https://x.com/DGMJK/status/1830410916992516440

Another user confirms the same experience:

[–]SpaceForceAwakens "I think you're right, and I'm 99% sure of it, because I have a similar noise sometimes.

I have a Wyze camera set up in my bedroom. It faces out to my front door so that I can see when I'm getting a delivery. It has a microphone.

I have it streaming through my home wi-fi to my TV. When I get an alert that there's a vehicle approaching I turn on the TV and can see whatever the camera sees.

Thing is, if I make any noise, the camera mic pics it up. Because it's streaming via RTSP, there's about a half-second delay. Whatever it hears plays on my TV's speakers about a half second later.

But the camera hears that, and plays it back through the TV again. And it gets louder each time, too. If I can't find my remote to mute the TV then I would have this exact noise coming from my TV every time I press a button on my TV remote. It makes a "boop" sound, and when it feeds back enough, it sounds exactly like what they're hearing.