Nearly all normal-hearing babies produce delayed evoked otoacoustic emissions

Evidence

Objective measurements, however, can be used in cases where it is not possible to communicate with the human subject. Babies only a few months of age are typical cases. It is very important to determine as early as possible whether the hearing system acts normally or abnormally. To make such a decision, the measurement of delayed evoked otoacoustic emissions in babies can produce helpful information. Almost 98% of normally hearing subjects, including babies, produce these emissions. Therefore, their lack can be used as an indication that the development of the inner ear is at least not normal, or that the middle ear strongly attenuates the sound transmission. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1873

Categorization

• SHARE: The specific 98% figure and the diagnostic use (absence of emissions flags inner/middle ear problems) is a neat clinical fact for anyone in audiology or pediatric medicine.
• QUESTION: Why 98% rather than 100%? What fraction of normal-hearing adults and babies fail to produce emissions, and does that affect diagnostic specificity?