As verbs the difference between mattering and muttering
is that mattering is present participle of matter while muttering is present participle of lang=en.
As a noun muttering is
something which is muttered.
muttering
English
Verb
(head)
Noun
(
en noun)
Something which is muttered
- I managed to catch a few of his mutterings .
A rumour.
Synonyms
* (something muttered) mumblage