Hi Piemistress, the waiting is stressful, sorry you are going through this. IME 10 months seems awfully long to wait, and not quite right. There is an awful lot of speech & language development during this time and I would be really surprised if they insisted on you waiting this long (unless they are confident that the hearing loss is very mild and not impacting her ability to hear you well for now).
Our DD failed the newborn screening and was referred at 2-3 weeks and having failed that was referred again a week later and had her hearing aids fitted by 5 weeks or so. (She has a moderate sensorineural hearing loss both ears). They initially suggested delaying because they thought she could be congested from a CS birth and we had confirmed that she was a very snuffly newborn and blocked up, which could have affected the hearing (this only turned out to have about a 10dB impact though). When we asked why she couldn't be tested sooner they said congestion / colds in infants can take much longer to clear than adults with colds. They said come back in 4-6 weeks but we pushed to come back sooner and they were happy to do that.
A lot depends on where you are too, Pie. A new friend of mine who's daughter was born on the same day in the same hospital but lives in the next door borough has had quite different care from us, the differences are quite extraordinary! (NHS have already provided us with a Teacher of the Deaf and a Speech Therapist, who come to the home as often as we wish, on top of all the fantastic genetic investigations and audiologist testing etc etc they are doing, I have been astounded - DD is 16 weeks!!)
Also, if you baby has glue ear (our DD had this too, which cleared up after about 2 months) this will have an impact on hearing levels. In our case, about 10dB across all frequencies. Yes, glue ear will clear up, it is not permanent but it can recur throughout childhood and kids who are repeatedly effected will often be fitted with grommets (surgery) to drain the fluid on the ear. So yes, a 7 week old (and indeed a 7 year old!) can have fluid on the ear, it can take several months to clear up in the first instance and simple and quick (a matter of seconds) tests by your audiologist can detect whether fluid is present.
Yes it is difficult to test the hearing of a 7 week old baby - if they are awake 
- note that the hearing tests they do at this point though are when the baby is sleeping (and the older they get, the harder it is, more tests at 3 months were so much harder than those at 1 month!) Providing the baby is sleeping, they will get a good picture of hearing by measuring brain activity objectively across all frequencies using the electrodes as you say.
When you say 'quiet' - do you know what dB and at which frequencies? (I admit there is SO much to take in throughout all these tests and appointments, it took us a while to figure it all out).
HTH and good luck, let us know how you get on.