The theory of loudness recruitment has been formulated by Fowler.1 Clinically, this phenomenon is utilized to distinguish between a conduction impairment and a nerve defect. In the words of Fowler, "The recruitment of loudness with intensity enables one to diagnose obstruction from nerve deafness." By means of the loudness balance test, it has become possible to make a quantitative determination of the degree of recoupment. The results vary. Most patients with "nerve" deafness of undetermined origin show considerable recruitment to sounds of the higher frequency range; some patients possess this factor to a minimal extent; a few are devoid of it altogether. In acoustic trauma, the 4096 wedge is usually devoid of this phenomenon. The individual with a high tone impairment frequently possesses this factor to a remarkable degree. In a series of 20 patients with degeneration of the acoustic nerve, studied by Dix, Hallpike and Hood,2 slight loudness recruitment
SALTZMAN M. RECRUITMENT PHENOMENON IN CRANIOCEREBRAL TRAUMA: Report of Representative Cases. AMA Arch Otolaryngol. 1950;52(5):782–785. doi:10.1001/archotol.1950.00700030808009
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