Do I need to fit a threshold seal - and if so, why?

I've heard about Document E - but how does it relate to doors?

I need to achieve the highest acoustic rating possible on a standard door, can you help?

I need to fit a glazing panel into a door that also needs to provide acoustic performance. How can I do this?

If I fit a drop seal, do I need to fit a threshold plate too?

What standards and regulations relate to acoustic containment for doors?

I've heard that some seals on the market can achieve acoustic ratings of around 40-50dB Rw. Is that right?