For what it's worth - I've been Deaf on my right side, since birth... slowly I acquired mild/mod flux loss on my left as well...
I've ALWAYS had difficultly setting my voice at the "right" level ... I typically speak too loudly - because even with hearing aids - it's impossible for ME to know what normal to YOU is (I can only play the "this sounds a bit quiet to me, so i need to increase my voice, or this sounds loud in my head, so I should speak quieter. I can only gauge my voice against other voices and then attempt to match that volume (it's actaully very very hard to do!)
My family is used to this, and is constantly (as in 5-20times daily) letting me know that I'm either speaking loudly, or rarely) whispering too quietly compared to others.
Another thing is that I do tend to be a bit "loud" compared to hearing people ... I walk very softly (minimize walking vibrations, that in the deaf world would be an "attention getting" technique) however I tend to forget not to close doors, put cutlery away in the drawer loudly, play music etc at a hearing volume etc. When I was living on my own, this wasn't an issue - and I forgot to be "careful" about making sounds ... now that I'm living with a hearing person, I have to be intentional about being quite.
It's very hard to act hearing !! (without being able to monitor the volume of things yourself in the same way that hearing do)
Of course ... I see things in my peripheral vision, and pick up very subtle vibrations etc MUCH better than any of my hearing friends or family ... because I use my eyes as "visual ears" - if that make sense
The only advice I can offer to people, including parents with Hoh kids - is to be patient, understanding and find a way to help the hoh person/child monitor their voice in a discrete but clear way ... be it using a gesture of "softly" or "higher/louder" or using a consist (but not judgmental) phrases like "a bit softer voice" , or "a bit louder voice" ...
Keep in mind that it's normal to have to re-adjust the hoh person throughout a conversation, when entering different rooms, or if there is background noise (I can't hear my voice at all sometimes if there is much background noise ... making it very hard to know how loud I am speaking.)
In general - Hoh people (even little kids) are working VERY hard to hear, understand and have their voice "match" other people (in articulation, modulation, volume etc).
Please know that if a you notice the Hoh person in your life is having difficulty with volume etc - it's because it is a genuine & constant challenge that is VERY difficult to manage... NOT because they are intentionally being "difficult" , trying to "act out" or "get attention" etc.
Although I was raised "oral only" (just listening and speech) I can't say enough about how ASL helped me, not only communicate in ASL with other signers, but also helped my English - having English concepts and word usage explained to me in ASL allowed me to understand in an un-inhibited way how language, and how English "worked".
While working on speech skills is certainly important ... it's absolutely critical that you don't make the mistake of thinking that your child must speak in order to be successful or happy. The earlier children learn language - ANY language, the better they will be able to acquire language(s) in the future ... this is one of the reason why so many of us hoh and Deaf recommend to parents that they start using ASL in addition to English. ASL will give the child a strong language base, on which they can build both ASL proficiency as well as English .. so while you are diligently working on speech, listening and reading skills - please consider the advantages of also using ASL signs as a means of giving him a way to connect "things" with language while he learned how to make sense of the garbled sounds of language that "is being Hoh".
For what it's worth ... my parents, who where both adamant that I NOT learn ASL as a child ... now wish desperately that I'd had that chance to learn it that young after all - they've both taken ASL classes, and now "get" that learning ASL does not negatively impact English at all. My mum, ironically has worked with many young Hoh and Deaf children in the school system since my youth, and has seen the positive difference that ASL makes in the students she works with ... she frequently says "If I'd only known that it would have helped!!"