I think it is a good idea for a hearing person to try out what it is like to be deaf by using the earplugs. I don't know if that work to keep sounds out or just muffle out the sound. She will have first hand in experiencing what it is like to be deaf.
I remembered that someone told me at the Hearing Society that when a new person who is hearing find the place so quiet but will like to try wearing a sort of like hearphones, only that it is quiet so that hearing person can not hear the sounds at all. It will help the hearing person understand why deaf people can not hear, even with hearing aid for pick up words which is difficult not understanding the words. Most often it is the environment sounds that we hear which is not accurate.
If you are hard of hearing, then you know what it is like when it come with no sounds or manage to hear with muffled sounds. You said that your boyfriend said that you are hard of hearing so you must be as you have tinnitus and you are experiencing hard to understand what people said. Do you have hearing aid(s)? If you do, then you are HOH. If not, then you need to go to the audiologist to get hearing test to see how much you have lost your hearing. But for Llanderr, she is fully hearing and did not know what it is like to be deaf so she had to tried and find out why the deaf has a hard time not hearing the sounds.
Mew, will you quit making rude remarks when she is interest in understanding about deafness and Deaf Culture. She want to sign with her boyfriend. She might pretend to be deaf but she wanted to learn about the experience of being deaf. It won't last anyway. Just like people who are not blind want to know what it is like to be in the dark and never be able to see at all. They used blindfold (usually the black cover pads over their eyes). They are curious about blind people.