If the background music (PSP_GAME\SND0.AT3) is an atrac3plus audio it will not played when the game is viewed on the UMD ISO/CSO Browser.
Yet we have many way to convert .at3 to .wav files.
My suggestion is convert PSP_GAME\SND0.AT3 to tmp\UmdBrowserCache\isoNname\SND0.wav and play it.
Yet we have many way to convert .at3 to .wav files.
My suggestion is convert PSP_GAME\SND0.AT3 to tmp\UmdBrowserCache\isoNname\SND0.wav and play it.