Question about Traveller's Shriekers

[nerdvana]

I'm re-reading the aliens of Traveller (Alien Races #4) and I'm curious about a trait that their description says they should have but that isn't listed in their writeup in that book. In the text on p109 it say...

Originally Posted by Alien Races 4, p109

while speaking, a Shrieker cannot hear.

That said, this is not in their write up on p114. (I would expect Deafness with some level of accessability limitation, perhaps at -75% to make it a -5 point disadvantage.) What do the rest of you think of this?