An iLounge report claims that has discovered differences in the quality of sound recorded by the microphones on numerous Wi-Fi and 3G iterations of the Apple iPad 2. The Wi-Fi-only models of the iPad 2 are said to be recording sound in the best quality among all other models.
Why the difference? Essentially, the differences are due to the fact that the microphone opening in the Wi-Fi iPad 2 is at the center of the top edge of aluminium surface of the tablet while the surface differs on the 3G models, which is black plastic. It should be known that the GSM and CDMA iterations of the iPad 2 are slightly different in behaviour.
Perhaps due to this change in materials, the Wi-Fi model offers markedly cleaner audio than that of the 3G, which sounds slightly muffled and echo-prone as a result. Curiously, we found the GSM 3G model's audio to be slightly preferable to that of the CDMA model, which seemed to suffer the issues more severely.
The report says that the differences are noticed when the iPad is held facing the user, which would be the typical stance when FaceTime or similar apps are being used.In the original iPad, the microphone was located next to the headphone jack on the top edge, however, it looks like Apple put the microphone in the centre on the iPad 2 in order to increase the sound reception, particularly for the usage of FaceTime and similar apps.
So if this report is something to go by, it seems like the acoustical qualities of the black plastic strip housing the antenna in the 3G flavour of the iPad 2 performs relatively lower as compared to the Wi-Fi version of the iPad 2.