My Pdog has not made any noises at all since I got him.
I got a new pdog on the 10th of this month (June) and so far he has not made one single pdog noise. I work from home (and am also a homebody) so I am home the majority of the time and in that time not one yip or anything. Not when I sneeze, cough or even come in the house. I live in a very small house and would be able to hear the pdog from any room so I highly doubt I have missed any noises (and again I am home pretty much all the time).
My pdog is approx. 4 months old and is still getting used to me. I try to hold him/her (not 100% sure just yet) about 3 times a day for 1 to 3 hours at a time. I also put my hand in his/her cage and play with him/her throughout the day. I don't feel that at the moment we are comfortable enough with each other to let him just run around the house (just yet anyways).
The pdog does seem to like me (gives me love bites and wants attention) and I also give it lots of good healthy foods and it has various things to play with in it's cage. So I think it is somewhat happy so am thinking it isn't making noises because it is unhappy. Also seems healthy: eating, peeing and pooping normally.
Is it normal for young ones to not ever make any pdog noises? He also has not even did the throw his arms up in the air thing so it isn't like no noise is coming out.