Human voice production for speech is an inefficient process in terms of energy expended to produce acoustic output. A traditional measure of vocal efficiency relates acoustic power radiated from the mouth to aerodynamic power produced in the trachea. This efficiency ranges between 0.001% and 1.0% in speech-like vocalization. Simplified Navier–Stokes equations for non-steady compressible airflow from trachea to lips were used to calculate steady aerodynamic power, acoustic power, and combined total power at seven strategic locations along the airway. A portion of the airway was allowed to collapse to produce self-sustained oscillation for sound production. A conversion efficiency, defined as acoustic power generated in the glottis to aerodynamic power dissipated, was found to be on the order of 10%, but wall vibration, air viscosity, and kinetic pressure losses consumed almost all of that converted power. Thus, the acoustic power, reflected back and forth in the airway was dissipated at a level on the order of 99.9%, with a small fraction being radiated to the listener.

就用于产生声音输出的能量而言，用于语音的人类语音产生是低效的过程。传统的声音效率测量方法是将从口腔辐射的声功率与气管中产生的空气动力相关。像语音一样的发声效率在0.001％到1.0％之间。从气管到嘴唇的非稳态可压缩气流的简化Navier–Stokes方程用于计算沿气道的七个关键位置的稳定空气动力，声功率和总功率。允许气道的一部分塌陷以产生自持振荡，以产生声音。甲转换效率被定义为声门中产生的消散了空气动力的声功率，大约为10％，但是壁振动，空气粘度和动压损失几乎消耗了所有转换后的功率。因此，在气道中来回反射的声功率以大约99.9％的水平被消散，其中一小部分被辐射到听众。