一项研究报告说，一些灵长类动物比其他哺乳动物能更精细地分辨出复杂声音的频率。
声音在耳蜗中产生振动，这能带来听觉所需的神经信号。
耳蜗把声音分解为成分频率的能力称为频率调谐，它对于识别声音及其位置具有关键作用。Christopher Shera及其同事测量了猕猴的频率调谐。
猕猴是比猫、豚鼠和毛丝鼠—这些动物的听觉经常得到研究—与人类亲缘关系更近的灵长类动物。通过释放另一种声音，测量耳蜗对声音响应的时间可以间接测量频率调谐。
猕猴的耳蜗声释放延迟介于人类和这些常见的实验室动物之间。这组作者还记录了来自猕猴个体的听神经纤维的响应，结果发现它们的频率调谐比在常见的实验室动物身上观察到的显著更敏锐，但是类似于估计的人类最高频率的频率调谐。
这组作者报告说，精细地分辨音频的能力可能是灵长类动物的一个一般属性。这组作者提出，这些发现可能有助于科研人员开发听觉修复的算法，从而缓解听力丧失。（生物谷 Bioon.com）
doi:10.1073/pnas.1105867108
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Frequency selectivity in Old-World monkeys corroborates sharp cochlear tuning in humans
Philip X. Joris, Christopher Bergevin,, Radha Kalluri, Myles Mc Laughlin, Pascal Michelet, Marcel van der Heijden, and Christopher A. Shera
Frequency selectivity in the inner ear is fundamental to hearing and is traditionally thought to be similar across mammals. Although direct measurements are not possible in humans, estimates of frequency tuning based on noninvasive recordings of sound evoked from the cochlea (otoacoustic emissions) have suggested substantially sharper tuning in humans but remain controversial. We report measurements of frequency tuning in macaque monkeys, Old-World primates phylogenetically closer to humans than the laboratory animals often taken as models of human hearing (e.g., cats, guinea pigs, chinchillas). We find that measurements of tuning obtained directly from individual auditory-nerve fibers and indirectly using otoacoustic emissions both indicate that at characteristic frequencies above about 500 Hz, peripheral frequency selectivity in macaques is significantly sharper than in these common laboratory animals, matching that inferred for humans above 4–5 kHz. Compared with the macaque, the human otoacoustic estimates thus appear neither prohibitively sharp nor exceptional. Our results validate the use of otoacoustic emissions for noninvasive measurement of cochlear tuning and corroborate the finding of sharp tuning in humans. The results have important implications for understanding the mechanical and neural coding of sound in the human cochlea, and thus for developing strategies to compensate for the degradation of tuning in the hearing-impaired.
