Source : Webster's Revised Unabridged Dictionary (1913)

Tootle \Too"tle\, v. i. [imp. & p. p. {Tootled}; p. pr. & vb. n.
   {Tootling}.] [Freq. of toot.]
   To toot gently, repeatedly, or continuously, on a wind
   instrument, as a flute; also, to make a similar noise by any
   means. ``The tootling robin.'' --John Clare.

Source : WordNet®

tootle
     n : sound of tooting softly and repeatedly as on a flute
     v : toot continuously; "tootling car horns"