Zhongping Mao, Lijun Zhao, Lichun Pu, Mingxiao Wang, Qian Zhang, David Z. Z. He

With advancements in modern medicine and significant improvements in life conditions in the past four decades, the elderly population is rapidly expanding. There is a growing number of those aged 100 years and older. While many changes in the human body occur with physiological aging, as many as 35% to 50% of the population aged 65 to 75 years have presbycusis. Presbycusis is a progressive sensorineural hearing loss that occurs as people get older. There are many studies of the prevalence of age-related hearing loss in the United States, Europe, and Asia. However, no audiological assessment of the population aged 100 years and older has been done. Therefore, it is not clear how well centenarians can hear. We measured middle ear impedance, pure-tone behavioral thresholds, and distortion-product otoacoustic emission from 74 centenarians living in the city of Shaoxing, China, to evaluate their middle and inner ear functions. We show that most centenarian listeners had an "As" type tympanogram, suggesting reduced static compliance of the tympanic membrane. Hearing threshold tests using pure-tone audiometry show that all centenarian subjects had varying degrees of hearing loss. More than 90% suffered from moderate to severe (41 to 80 dB) hearing loss below 2,000 Hz, and profound (>81 dB) hearing loss at 4,000 and 8,000 Hz. Otoacoustic emission, which is generated by the active process of cochlear outer hair cells, was undetectable in the majority of listeners. Our study shows the extent and severity of hearing loss in the centenarian population and represents the first audiological assessment of their middle and inner ear functions.