What causes Pokemon x and y to freeze?

What causes Pokemon x and y to have no audio and freeze when ever you receive something?

No audio… That looks like a new issue. But freezing is common. Citra is not yet ready with texture rendering. Look this up.

The game is just silent except for when you press a button .

Lack of audio is normal in X and Y. If we knew why something was happening, then we could probably fix it. But no one has looked into the issue, besides preliminary glances.