to mumble, to mutter [verb] [mompelde, gemompeld] [‘mom-pu-lun’]

Examples:
– "Je moet niet zo mompelen, maar duidelijk praten!"
("Don’t mumble like that, speak up clearly!" Lit.: "You must not mumble like that, but talk clearly!")

– "Kon jij Frank verstaan? Hij zat echt onverstaanbaar te mompelen tijdens de vergadering…"
("Could you hear what Frank was saying? He was mumbling really unintelligibly during the meeting…")

– " ‘Ik heb hier helemaal geen zin in’, mompelde Hermelien zachtjes, toen ze de kamer van professor Sneep binnenstapte."
(" ‘I really don’t want to do this’, muttered Hermione quietly, when she entered professor Snape’s room.")

Related words:
– "Articuleren": to articulate.
– "Binnensmonds spreken": to speak inarticulately (lit. "to speak within/inside the mouth").