The term BROOK SOUND refers to the sound of a stream or brook. MURMUR, with 6 letters, is a low, continuous sound, like that of a stream flowing over rocks. GURGLE, also with 6 letters, is a bubbling sound made by water running through a narrow channel. TROUT, with 5 letters, is a type of fish that can be found in streams and brooks. PURL, with 4 letters, is a type of wave-like sound made by a stream or brook. All of these words describe the sound of a brook or stream.