sends two frequency tones through each of the headphone’s earbuds, detects the distortion-product OAEs generated by the cochlea and recorded via the microphone. Such low-cost technologies may help larger efforts to achieve universal neonatal hearing screening across the world. See also Auditory brainstem response Entoptic phenomenon Maryanne Amacher, a composer who used this phenomenon in her music Pure tone audiometry The Hum References Further reading M.S. Robinette and T.J. Glattke (eds., 2007). Otoacoustic Emissions: Clinical Applications, third edition (Thieme). G.A. Manley, R.R. Fay, and A.N. Popper (eds., 2008). Active Processes and Otoacoustic Emissions (Springer Handbook of Auditory Research, vol. 30). S. Dhar and J.W. Hall, III (2011). Otoacoustic Emissions: Principles, Procedures, and Protocols (Plural Publishing). Acoustics Hearing Ear procedures