Where can I find the Minecraft sound folder?

I hope somebody can help me, I'd like to change sounds in Minecraft but the problem is I can't find the audio files anywhere, I'm using this new launcher and have downloaded different versions. In addition, I have some mods on it, but can only find the sounds for the villagers. And the strange thing is minecraft is running and the sounds are all there just can't find them.

On minecraftforum.de