The size of a bank depends largely on its compression format and quality settings. Similarly, the size of your audio assets depends on the compression format of those audio assets. If your audio assets use a extremely small compression format, and your banks use a comparatively large format and higher quality, your banks will be larger than your original assets.
To reduce the size of your built banks, try changing your banks’ encoding formats and adjusting their quality or sample rate settings. In FMOD Studio versions 1.07 and earlier, you can change these settings in the Event Editor window while viewing the Banks browser. You will have to experiment and consult your target platforms’ requirements to find out what compression settings work best for your game.
Note that reducing encoding quality or sample rate may reduce the quality of audio produced by your game.
Note also that we recommend using uncompressed audio formats for your source audio assets. Uncompressed audio is easier to work with for sound design purposes, and the compression format of your assets in no way affects the compression format of your built banks.