If Adobe Premiere imports AVCHD footage but only plays the video and not the associated sound, here is a workaround:
Project FolderGo to your project folder and open the renamed AVCHD folder you transferred from the camera’s SD card to your computer.  (See the Video Footage Transfer tutorial for details.)
Show Package ContentRight-click (Control+click) on the BDMV folder and choose “Show Package Contents”  to reveal the STREAM folder.

Copy STREAM folderSelect the STREAM folder and copy it (Control+C).

Paste STREAM folder into project folder.Navigate to your project folder and paste a copy of the STREAM folder (Control+V).
Rename folder.Rename the STREAM folder with the name of the AVCHD folder followed by STREAM.  In this example, the original folder is Basic-1, and the new STREAM folder is Basic-1-STREAM.

Import your new STREAM folder into Premiere. Both the video and sound should play for each file. Import new folder into Premiere