Is this just a bug in ios 6? The music volume seems fine, but you really have to turn it all the way up to hear the lock and keyboard sounds.
I noticed that same thing when I was playing w/ my wife's new iPad 4.
Solution is in the link: https://forums.macrumors.com/threads/1495271/
This problem has not been resolved. The issue in the thread posted above is a common user error with the 'Change with Buttons' option.
There is an audio bug in iOS 6 that reduces the lock/unlock and keyboard click sounds about 50% lower than all other sounds at the user selected level.
For example, there are 16 sound levels. I prefer to have my alert sounds and ringtones set to 8. So, I set them to level 8 (half way), then select not to 'change with buttons' so that this alert sound preference is locked in.
When you toggle the 'Lock Sounds' and 'Keyboard Clicks' buttons on and off in System Settings, they are at normal (level 8) volume. The problem is, when the iPad actually uses these sounds to lock/unlock, etc., they playback at sound level 3 or 4.
Even after you turn on 'Change with Buttons' the play-black of the lock/unlock sounds are still greatly reduced. I've only seen this on iPad 3's and iPad 4's with iOS 6.