The effect of blowing pressure, lip force and tonguing on transients: A study using a clarinet-playing machine.

Wind instrument players control the initial and final transients of notes using breath, lips, and tonguing. This paper uses a clarinet-playing machine and high-speed camera to investigate how blowing pressure, lip force, and tonguing parameters affect transients. After tongue release, the reed quickly comes to rest, losing its mechanical energy. However, the changing aperture past the reed rapidly changes the airflow. For pressure above the oscillation threshold, successive interactions between reflections of this pulse of airflow and the reed produce an exponential increase in the sound. The rates r of exponential increase in the fundamental of the sound range from several tens to several hundreds of dB s(-1), as functions of blowing pressure and lip force. Because the reed's initial mechanical energy is lost, tongue force and acceleration have little effect on r. However, larger tongue force and acceleration produce more rapid changes in flow, which start notes sooner after tongue release. Further, large tongue force increases the third harmonic during the transient. There is a hysteresis region on the (pressure, lip force) plane where regenerative oscillation is not produced spontaneously by increasing blowing pressure only. Here, tongue action can initiate sustained notes at low pressure.