mumblegerund / present participle Used attributively to modify nouns meaning ‘engaged in mumbling’ or ‘producing low indistinct sound’ (e.g., "mumbling voices").
marmonnantAdjectif participial : qui parle d’une voix basse et indistincte. The recording was full of mumbling vocals that were hard to decipher.
L’enregistrement était rempli de voix marmonnant, difficiles à déchiffrer.