As i am using instructional audios in my game and there are big files so my app size is getting bigger so pleas anyone tell me how to reduce audio file size - i have heard about Android obb tool but don't know how to use it ,

or if there is another way to direct download the audio files from a server inside the app ( as big game app downlaods the resources from the server ?)

i have more 20 big instructional audio files .