One of the important challenges in the study of wind instruments is to understand how a “dc” input (i.e., the air jet established by a player) is converted to an acoustic oscillation. To study this problem, the time dependences of the pressure and flow velocity of air as functions of position in the mouthpiece region of a soprano recorder under realistic playing conditions have been obtained using first principles simulations, and used in a straightforward mechanical analysis to determine the regions where energy at the acoustic frequency is generated. This analysis also describes the direction of the “flow” of acoustic energy through and away from the mouthpiece region. Since our analyses of energy generation and flow do not depend on any assumptions about the role of vorticity in these processes, our results can be used to study and test theoretical predictions that posit the importance of vorticity, such as Howe's energy corollary, in the sound generation process. Work supported by the U.S. National Science Foundation through grant PHY-2306035.
N. Giordano (Wed,) studied this question.