He is not angry. He just cannot hear himself. Hearing loss comes on slowly. The person with it is usually the last to notice. This is the Volume Creep pattern. A direct correction in front of other people embarrasses him. These approaches work around that.
Practical Techniques
Change the Room First
Reduce background noise before the conversation starts. Turn off the TV. Sit closer to him. A quieter room means he does not have to project. He adjusts without noticing he adjusted.
Use a Signal You Agreed On in Advance
Set this up in private, before you need it. Pick something simple: a touch on the arm, a hand briefly placed on the table. When you use it during a conversation, he knows what it means. Nobody else does.
Say Something, but Blame the Room
If a signal is not possible, address the volume out loud. Frame it around the environment. Say: “It is a bit loud in here. Could we speak a little softer?” This gives him a reason to adjust. It is not a criticism of him.
For a more direct conversation in private: “I notice your voice carries a lot when there is background noise. Mine does too.”
Why This Works
He does not intend to be loud. You are not correcting bad behavior. You are filling a gap he cannot fill himself. A method that keeps his dignity intact works. A public correction does not.
When to Raise the Hearing Topic
Volume that keeps increasing over months is worth a private conversation about hearing health. Say: “I have noticed your hearing seems harder lately. Would you be open to getting it checked?” Bring it up separately from any social situation.