Dr. Aaron Johnson is a researcher and speech-language pathologist specializing in voice debilitation and rehabilitation. His research laboratory is funded by the National Institutes of Health. He uses novel translational research methods to examine the effects of vocal training on laryngeal neuromuscular mechanisms in the aging larynx. His professional background includes a decade-long experience serving as a classical singer and teacher of singing.

Dr. Johnson began Part 2 of his presentation regarding how the idea of exercise is to have some sort of repeated muscle use or stress designed to induce specific adaptations. The goals are to increase the strength or endurance of the muscles. Vocal exercises are built on both sides of the continuum. Endurance training involves a long duration of this activity under low load with high repetitions so we can have a power output over longer periods of time. With resistance training, we are thinking of short durations of activity with high load and typically not many repetitions. Resistance training with the voice is trickier to apply. He referred to his work at the University of Wisconsin prior to arriving at NYU. He discussed the advantages of using a rat model based on ultrasonic vocalizations. Rats produce these by using the same underlying laryngeal neuromuscular mechanisms that we use to produce our vocalizations as humans. He showed a video of how rats are trained and discussed some findings of research that was undertaken, showing how louder vocalizations were achieved. Another study included younger rats and changes in muscle fiber type composition.