soughing

(verb) make a murmuring sound. Synonyms: sough, purl. Example: "The water was purling."

(adj) characterized by soft sounds. Synonyms: murmurous, rustling, susurrous. Examples: "A murmurous brook." "A soughing wind in the pines." "A slow sad susurrous rustle like the wind fingering the pines"- r.p.warren."