Making a low continuous indistinct sound:
— Susurrant voices.

synoniemen: murmuring, whispering.

Roget 405: inaudible; scarcely audible, just audible; low, dull; stifled, muffled; hoarse, husky; gentle, soft, faint; floating; purling, flowing etc. v.; whispered etc. v.; liquid; soothing; dulcet etc. (melodious) 413; susurrant^†, susurrous^†.    ... meer laten zien