Recent experiments using a portable, extremely low‐power electromagnetic motion sensor to detect the motion of the posterior tracheal wall during speech production will be presented. The motion of the wall may be related to the driving subglottal pressure through a lumped element circuit model, leading to an approximation to the voiced excitation function of the human vocal tract. Using the excitation and the recorded spoken audio, a stable and accurate transfer function of the vocal tract may be calculated every few glottal cycles in near real‐time. The excitation function may be used to calculate very accurate pitch information at low cost, and the transfer functions may be employed as an additional feature vector to enhance the performance of a new class of speech recognizers and synthesizers. [Work supported by NSF and DOE.]