I think your problem comes from a problem with what you are playing.
Did you manage to play this sound before putting the sounds in the obb ?
Because on android you cannot preload a sound that once decompressed in memory takes up more than one MB.
Here you should use playBackgroundMusic instead of playEffect (that always preload the sound if it is not already preloaded) which will use instead Cocos2dxMusic.java of Cocos2dxSound.java
Am able to play sound before putting the sounds in the obb. And my sounds file size is less than 1 MB.
I rechecked with these things. Still am not able to play sounds.
Yes. I tried playing sound by using playBackground music. It will not crash. Am getting error message as i posted above.
Yes. i have changed both java file.
Sorry I do not have any ideas why it does not work.
If your music files are not too big you could perhaps keep them in the apk and still be under the 50 mb limit.