Possible hearing loss

[SpringCrane]

Hi all. My son is almost 9 months old, and he hasn't started any babbling yet. He makes a lot of other noises, cooing/shrieking/laughing, but no dada, baba, etc. I started testing to see if he reacted to my voice or other moderate sounds (snapping, etc.), and he doesn't always look over at the source of the noise. He does sometimes, but it's hard to tell when he's just coincidentally looking. He does react to loud noises consistently. He had a newborn hearing test and passed. I emailed his doctor, and since we are getting ready to fly, she suggested we check to see if there's fluid or infection causing the problem. We went in this morning, and he does have a little clear fluid in one ear, which she thinks is leftover from colds a couple of months back. He's been referred for a hearing test and we have a "developmental questionnaire" to fill out and send in.

I was hoping his doctor would just say, "Oh, he has plenty of time to start babbling, don't worry!" But I guess something might actually be wrong.

Has anyone dealt with hearing/communication issues with their LOs?