A:
The Sony ICDAX412 Digital Voice Recorder requires 2 AAA Alkaline batteries. The Negative end of the battery has to be placed towards the spring side in the battery compartment. The Positive and Negative symbols would be indicated in the battery compartment.
You can also refer the Page # 11 in the Manual provided below to view the steps on how to install the batteries in to the Sony Digital Voice Recorder.
http://www.docs.sony.com/release/ICDAX412_EN.pdf