Department of Otolaryngology/Head and Neck Surgery, University of North Carolina, Chapel Hill, North Carolina, USA.
Ear Hear. 2021 May/Jun;42(3):691-699. doi: 10.1097/AUD.0000000000000975.
The purpose of this study was to measure low-rate binaural frequency modulation (FM) detection across the lifespan as a gauge of temporal fine structure processing. Children and older adults were expected to perform more poorly than young adults but for different reasons.
Detection of 2-Hz FM carried by a 500-Hz pure tone was measured for modulators that were either in-phase or out-of-phase across ears. Thresholds were measured in quiet and in noise. Participants were school-age children (n = 44), young adults (n = 11), and older adults (n = 17) with normal or near-normal hearing.
Thresholds were lower for out-of-phase than in-phase modulators among all listening groups. Detection thresholds improved with child age, with larger effects of age for dichotic than diotic FM. Introduction of masking noise tended to elevate thresholds; this effect was larger for the dichotic condition than the diotic condition, and larger for older adults than young adults. In noise, young adults received the greatest dichotic benefit, followed by older adults, then young children. The relative effects of noise on dichotic benefit did not differ for young adults compared to young children and older adults; however, young children saw greater reduction in benefit due to noise than older adults.
The difference in dichotic benefit between children and young adults is consistent with maturation of central auditory processing. Differences in the effect of noise on dichotic benefit in young children and older adults support the idea that different factors or combinations of factors limit performance in these two groups. Although dichotic FM detection appears to be more sensitive to the effects of development and aging than diotic FM detection, the positive correlation between diotic and dichotic FM detection thresholds for all listeners suggests contribution of one or more factors common to both conditions.
本研究旨在测量一生中低频双耳调频（FM）检测，以作为时间精细结构处理的指标。预计儿童和老年人的表现会比年轻人差，但原因不同。
使用 500Hz 纯音携带的 2Hz FM 进行检测，调制器在耳间同相或异相。在安静和噪声中测量阈值。参与者为学龄儿童（n=44）、年轻成年人（n=11）和听力正常或接近正常的老年人（n=17）。
在所有听力组中，异相调制器的阈值均低于同相调制器。检测阈值随儿童年龄增长而降低，双耳比单耳 FM 的年龄效应更大。掩蔽噪声的引入往往会提高阈值；这种影响在双耳条件下比单耳条件下更大，在老年人中比年轻人中更大。在噪声中，年轻成年人获得最大的双耳优势，其次是老年人，然后是幼儿。噪声对双耳优势的相对影响在年轻成年人与幼儿和老年人之间没有差异；然而，幼儿由于噪声导致优势减少的幅度大于老年人。
儿童和年轻人之间双耳优势的差异与中枢听觉处理的成熟一致。幼儿和老年人中噪声对双耳优势影响的差异支持这样一种观点，即不同的因素或因素组合限制了这两个群体的表现。尽管双耳 FM 检测似乎比单耳 FM 检测对发展和衰老的影响更敏感，但所有听众的单耳和双耳 FM 检测阈值之间的正相关表明，一个或多个共同因素对两种情况都有贡献。
