Everything works fine on the iPhone Models, using the volume buttons on the phone raise and lower the games audio. On iPad and iPod touch models volume buttons don't effect the games sound effects.
Here is the code I am using to play these short sounds.
-(IBAction) playClickSound {
CFURLRef mySoundUrl = CFBundleCopyResourceURL(CFBundleGetMainBundle(), CFSTR("click"), CFSTR("caf"), NULL);
SystemSoundID mySound;
AudioServicesCreateSystemSoundID(mySoundUrl, & mySound);
CFRelease(mySoundUrl);
// Plays the sound.
AudioServicesPlaySystemSound(mySound);
}