Ethan had a hearing test when i took him in for his PKU.
sometimes the clapping test is not a good one b/c they can detect vibrations, etc., so just b/c they look in that direction doesnt mean they actualy heard it.
E's hearing test involved putting sensors on his brain and hookign those up to the monitor (electrode type things...sorry i dont know more). the computer sends out signals and records how the brain reacts, so you know he is hearing the sound or not by brain activity. they are very nonintrusive IMHO and well worth it. its so much nicer than the hearing test they gave to ds2, which involved us being in a room with walls taht had different sounds inpeded in them and he had to react to the direction of the sounds.
i have also heard that when babies really excel at one or two things (in your case, an amazing physical ability compared to kiddos of the same age), that they have less energy for other milestones.
it may or may not be anything. or it may be hearing. or could simply be speech. ds2 had some speech issues and was in ST (speech therapy) for about 3 years. have you tried sign language? i know its the big hype now but for kiddos like my ds2 i was necessary b/c he couldnt communicate for a few years. he had a lot of problems, though b/c of other issues.
more than likely, your amazing dd is just totally focused on taking off around the house and considers talking to you guys 2nd on her to do list!!