Oh, come on, this is just being coy for no reason. Given the context, it is abundantly clear they mean "normal, human operated morse code".

A skilled operator is around 30 WPM. The average English word is 5 (rounded up) characters. Add one character for the space. That's 180 characters per minute, or 3 character per second. With 37 characters available in morse code, that's log_2(37) or 5.2 bits per charater.

So 15.6 bits per second. Just under half of the 39 bits they got for speech, like they said.