Mason A C, Morris G K, Hoy R R
Department of Zoology, Erindale College, Mississauga, Ontario, Canada.
J Comp Physiol A. 1999 May;184(5):543-51. doi: 10.1007/s003590050354.
Peripheral auditory frequency tuning in the ensiferan insect Cyphoderris monstrosa (Orthoptera: Haglidae) was examined by comparing tympanal vibrations and primary auditory receptor responses. In this species there is a mis-match between the frequency of maximal auditory sensitivity and the frequency content of the species' acoustic signals. The mis-match is not a function of the mechanical properties of the tympanum, but is evident at the level of primary receptors. There are two classes of primary receptors: low-tuned and broadly tuned. Differences in the absolute sensitivity of the two receptor types at the male song frequency would allow the auditory system to discriminate intraspecific signals from sounds containing lower frequencies. Comparisons of tympanal and receptor tuning indicated that the sensitivity of the broadly tuned receptors did not differ from that of the tympanum, while low-tuned receptors had significantly narrower frequency tuning. The results suggest that the limited specialization for the encoding of intraspecific signals in the auditory system of C. monstrosa is a primitive rather than a degenerate condition. The limited specialization of C. monstrosa may reflect the evolutionary origin of communication-related hearing from a generalized precursor through the addition of peripheral adaptations (tympana, additional receptors) to enhance frequency sensitivity and discrimination.
通过比较鼓室振动和初级听觉感受器反应，研究了螽斯科昆虫大怪螽斯（直翅目：怪螽科）的外周听觉频率调谐。在该物种中，最大听觉敏感性频率与物种声学信号的频率成分之间存在不匹配。这种不匹配不是鼓膜机械特性的函数，而是在初级感受器水平上就很明显。有两类初级感受器：低频调谐和宽频调谐。两种感受器类型在雄虫鸣声频率下的绝对敏感性差异，会使听觉系统能够区分种内信号与包含较低频率的声音。鼓室调谐和感受器调谐的比较表明，宽频调谐感受器的敏感性与鼓膜的敏感性没有差异，而低频调谐感受器的频率调谐明显更窄。结果表明，大怪螽斯听觉系统中对种内信号编码的有限特化是一种原始而非退化的状态。大怪螽斯的有限特化可能反映了与通讯相关的听觉从广义前身通过增加外周适应性（鼓膜、额外的感受器）以增强频率敏感性和辨别力的进化起源。
