Abstract
OBJECTIVES: The main objective of this study is to determine whether chronic sound deprivation leads to poorer speech discrimination in humans. DESIGN: We reviewed the audiologic profile of 240 patients presenting normal and symmetrical bone conduction thresholds bilaterally, associated with either an acute or chronic unilateral conductive hearing loss of different etiologies. RESULTS: Patients with chronic conductive impairment and a moderate, to moderately severe, hearing loss had lower speech recognition scores on the side of the pathology when compared with the healthy side. The degree of impairment was significantly correlated with the speech recognition performance, particularly in patients with a congenital malformation. Speech recognition scores were not significantly altered when the conductive impairment was acute or mild. CONCLUSIONS: This retrospective study shows that chronic conductive hearing loss was associated with speech intelligibility deficits in patients with normal bone conduction thresholds. These results are as predicted by a recent animal study showing that prolonged, adult-onset conductive hearing loss causes cochlear synaptopathy.