Read Bill Hunt on Audio Conforming http://forums.adobe.com/thread/726693
And... exactly what are you importing?
Codec & Format information, with 2 links inside for you to read http://forums.adobe.com/thread/1270588
Report back with the codec details of your file, use the programs below... A screen shot works well to SHOW people what you are doing
http://forums.adobe.com/thread/592070?tstart=30 for screen shot instructions
Free programs to get file information for PC/Mac http://mediaarea.net/en/MediaInfo/Download
Premiere Elements 12 on Windows 8 (assumed 64 bit).
Please update your Premiere Elements 12 to the 12.1 Update and let us know if you see any improvement in the performance, in particular any resolution of your audio issues. See opened project, Help Menu/Update for the 12.1 Update. Also...
More information is need about the properties of your source media, how you are importing your source media, and whether you are watching/listening to the rendered or unrendered Timeline content via the Edit area monitor.
In the cases where you have lost Timeline content audio, have you ever taken the Timeline to an export to determine if the audio is also lost in the end product?
Also, in the cases where you have lost Timeline content audio and you are working with the rendered Timeline content, have you found any resolution to the issue by moving the audio to an upper track and/or creating new track on which to place the video audio?
Please review and consider the above and then we can talk about what next based on your reply.