[jbuzbee]

Here's another magical experience. No one will believe it, but it's true, so here goes.

We too would read, sing and hum to my son in-womb. While doing so, we'd occasionally hear a loud click, the source of which we couldn't determine. But after he was born, we found out. He would press his tongue hard against the roof of his mouth then release it with a suction "pop". Was he trying to communicate back to us from the womb? We like to think so!

[m0zg]

I don't think this would work without air.

[pauljurczak]

Maybe it can. It's called cavitation.

[adrianN]

Are fetal tongues strong enough to induce cavitation? Are fetal mouths strong enough not to be shredded by cavitation bubbles collapsing? AFAIK cavitation kills a ship's screw sooner or later.

[pauljurczak]

Cavitation can develop with wide range of energies. In this case, I'm suggesting energy level sufficient to create an audible sonic click, but not high enough to rip infant's head off.

[thaumasiotes]

> He would press his tongue hard against the roof of his mouth then release it with a suction "pop".

This is an alveolar click, known as a normal part of certain African languages.

If you've seen the name "!Kung San" around, it is the sound indicated by the "!K".

[soyguzzler]

Reminds me of this: https://www.youtube.com/watch?v=U4okFm62gxk

[thaumasiotes]

Same click.