OAEs are considered to be related to the amplification function of the cochlea. In the absence of external stimulation, the activity of the cochlear amplifier increases, leading to the production of sound. Several lines of evidence suggest that, in mammals, outer hair cells are the elements that enhance cochlear sensitivity and frequency selectivity and hence act as the energy sources for amplification. One theory is that they act to increase the discriminability of signal variations in continuous noise by lowering the masking effect of its cochlear amplification.
Perhaps the first sign that this book would be a let down were the typos throughout the pages (such as "hunbands" for husbands p 211, "sores" for scores p 104). The carelessness of the authors was reflected in the poor quality of the content and its presentation. This book lacked a coherent voice, and others have noted the contradictory statements found throughout its pages.