iPad Pro microphone muffled output

I recently bought the new iPad Pro. It, of course, has the latest iOS 9 operating system installed. I have 2 children who live far away and I regularly FaceTime with them. They have both commented on how good the video looks, and both have told me that they have a hard time hearing me because the sound seems muffled. These comments were totally unprompted. My one child made the comment after I switched from my old 4th gen iPad. He said the sound on the old iPad was better. At first I thought maybe I was covering the microphone holes, but I was not. I did not have a case for the iPad at that time and there was no protective film covering the iPad. I did a little test yesterday by recording some video of me talking. When I played it back, unless the volume is turned all the way up, it does indeed sound muffled. I chatted with Apple support and they scheduled an appointment for me at the local Apple Store. I went there and told the technician about

my issue. He ran their standard diagnostics which only showed that the microphone works. And he took the iPad in the back to do some testing of his own. In the store it was crowded and loud. He said that he could te couldn't hear any difference of sound quality between my device and another and even let me listen with volume turned all the way up. Because of the noise in the store, it was really hard to tell much of anything. However, he said that we could do an exchange anyway which I thought was great. However, when I told him I bought it from Best Buy, he said they could not do the exchange and that I would have to go to Best Buy. I still may do this, but I was just wondering if anyone else had an issue like this with their iPad Pro. Is the sound quality of the microphone really inferior to the older iPads? Or, is there perhaps just a problem with mine?