OSA severity is indexed by apnea-hypopnea index (AHI), the number of apnea/hypopnea events occurring hourly during sleep. Our first aim is to determine NMTD's operating characteristics for treatment of OSA. The optimal duration of a detected apnea/hypopnea event before NMTD responds must first be determined. Additional adjustable features include sensitivity of respiratory event sensor, as well as pulse duration, frequency, and intensity of the delivered auditory tone. Since independent adjustment of each of the 4 parameters is not feasible, our screening analysis will test two variables at a time to identify which variables most effectively reduce AHI. This will allow for more practical titration during a therapeutic sleep study and more generalizable application of the device.