Door for sound reduction

[wakarimasen]

I am looking for some ideas to reduce sound from my son's bedroom (he talks and shouts loudly in his sleep). I don't know if replacing the hollow door in his room would help? Are there any other solutions for reducing noise?

Thanks

If you google 'sound proof doors' lots of ideas and options will appear. Choose which is best for you. Improving the current door or having a new one .