This paper reports a longitudinal study of a non-speech input-controlled continuous cursor control system: Whistling User Interface (U3I). This study combines quantitative (target acquisition tasks, subjective ratings and a simple reaction time test) and qualitative (interview) methods to arrive at a more nuanced understanding novice users' experience over time. The progress of training of ten participants has been observed. The study shows that the performance improved over time and plateaued on day four of the five days of the study. Keywords Voice-based interface, non-speech input, non-verbal control, mouse cursor, continuous input, acoustic gestures. ACM Classification Keywords H.5.2. Information interfaces and presentation: User interfaces -- Input devices and strategies (e.g., mouse, touchscreen); Voice I/O.