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I have misophonia. I sit next to my boss and he chews gum for hours on end every day. The nature of my misophonia means that it sends me into rage at the sound of the chewing. I have asked him not to chew gum when I'm around for this very reason but he either doesn't respect me or doesn't care. I have tried headphones but unless I have them too loud, it doesn't block the sound. He also frequently talks to me whilst chewing so I can't really avoid it then.
It makes me dread going to work every day.
How should I proceed? Go over his head to higher management who control the seating plan so I can be moved to another desk?