Yes, you can add background music into your created flipbook with our flipbook software (Boxoft PDF to Flipbook).
Here are steps in detail:
Step1: Launch Boxoft PDF to Flipbook software, and then browser PDF from your PC for conversion;
Step2: Select template from template list (Classical for example)
Step3: Find out Sound bar under Design Setting Panel (Design Setting -> Tool Bars Settings -> Buttons Bar -> Sound), and select enable option in “Enable Sound” bar, import sound file into “Sound File” bar.