What causes loud noices when flushings toilet and can a do it yourselfer fix it?

I had this problem when doing maintenance at an apartment complex. If the noise is coming from the pipes, you probably have air in the lines. Just go through and turn on all the faucets for about 5 minutes or so and it should help. If that doesn't work, you will need to look further into it.

What causes loud noices when flushings toilet and can a do it yourselfer fix it??
Please explain, in detail, what the noise sounds like? Where does ot come from? The tank or the bowl? Describe the noise? Roar? Howl?" Screech? Make me hear what you hear. Regards, Tom