It's meaningless chatter, or the soothing sound of a brook as it flows over stones
[DOC] [TLE] babble - definition and meaning - Wordnik [PAR] babble: To utter a meaningless confusion of words or sounds: Babies babble 
before they ... To talk foolishly or idly; chatter: "In 1977 [he] was thought of as 
crazy ... To make a continuous low, murmuring sound, as flowing water.