1. muffled is either 2. covered or 1. muted, the google definition of muffled includes the word 'muted' but it's google similarities includes the word 'covered' so i'm not sure what the answer could be :(
2. an inkling is definitely 4. a suspicion
3. irreparable is probably 2. permanent, because irreparable means "past the point of ever being repaired, not repairable"