Roget's Thesaurus of English Words and Phrases by Peter Mark Roget

405. Faintness — N. faintness &c adj.; faint sound, whisper, breath;

undertone, underbreath†; murmur, hum, susurration; tinkle; still small voice. hoarseness &c adj.; raucity†. V. whisper, breathe, murmur, purl, hum, gurgle, ripple, babble, flow; tinkle; mutter &c (speak imperfectly) 583; susurrate†. steal on the ear; melt in the air, float on the air. Adj. inaudible; scarcely audible, just audible; low, dull; stifled, muffled; hoarse, husky; gentle, soft, faint; floating; purling, flowing &c v.; whispered &c v.; liquid; soothing; dulcet &c (melodious) 413; susurrant†, susurrous†. Adv. in a whisper, with bated breath, sotto voce [Lat.], between the teeth, aside; piano, pianissimo; d la sourdine†; out of earshot inaudibly &c adj.. (ii) SPECIFIC SOUNDS