[W.]

I was going to say ultrasonic but you already did.

Anyone recall when desktop computers had little speakers you heard the dialup modem's handshake while it connected and the tinfoil crowd swore it was also a microphone? Yeesh.

[PapaBear3625]

Any speaker CAN be used as a microphone.

Now, whether the PC's electronics were enabled to take input from the speaker port is another story.

FYI, many current laptops come with an integrated microphone