The term 'murmuring sound' can be described by four different words: COO, SOUGH, PURR, and CURR. COO is a three-letter word that is used to describe the low, soft sound made by a dove or pigeon. SOUGH is a five-letter word that is used to describe a murmuring sound made by the wind in trees or through other objects. PURR is a four-letter word that is used to describe the low, continuous sound made by a cat. Lastly, CURR is a four-letter word that is used to describe a low, continuous sound made by a stream or brook. All of these words are used to describe a murmuring sound.