How do you use speakerphone in Android games?

Hey guys, I am making a phone game of sorts in which you hit gongs and other noisemaking stuff.

Is it possible to use the speakerphone instead of the regular speakers? With the volume up all the way you can barely hear it if there's any background noise in the room you are in.

I'll also accept any other useful suggestions about how I can make it louder. I've tried making the sound file louder but that makes it have lots of static.