thrum

thrum (http://definr.com/thrum)

     n : a thrumming sound; "he could hear the thrum of a banjo"
     v 1: sound with a monotonous hum [syn: hum]
     2: sound the strings of (a guitar or similar string instrument)
        [syn: strum]
     3: make a rhythmic sound: "Rain drummed against the
        windshield"; "The drums beat all night" [syn: drum, beat]