Acoustic reflex contraction of the stapedius muscle stiffens the middle-ear, thus decreasing middle-ear admittance; this can be measured thanks to tympanometry. The acoustic stapedius reflex can also be recorded by means of extratympanic manometry (ETM). As the stapedius muscle is innervated by the facial nerve, a measurement of the reflex can be used to locate the injury on the nerve. If the injury is distal to the stapedius muscle, the reflex is still functional. A measurement of the reflex can also be used to suggest a retrocochlear lesion (e.g., vestibular schwannoma, acoustic neuroma). The acoustic reflex normally occurs only at relatively high
The Life You Can Save book comes from the fact that Singer addresses readers directly, asking them what they will do about "the life "you" can save". Singer says that citizens of richer nations do not donate as much as they could. The author says the reasons are not philosophical, but due to psychological considerations including cognitive dissonance, diffusion of responsibility and the evolutionary history of human ancestors. For instance, according to Singer, cognitive dissonance theory predicts that humans are rationalizing creatures, making it difficult to change their minds on topics (e.g. charity) that cause any anxiety—unless they are highly motivated to bear it during