Studies on the Vocal-Auditory Functions of Primates

研究了黑猩猩和日本猴的基本听觉功能、对人类语言和同种声音的感知、对语言和声音感知的耳（半球）支配和早期声音发育。黑猩猩和日本猴表现出w形的听觉敏感功能。虽然它们对高频（高于8khz）更敏感，但对低频（低于250hz）和中频（2- 6khz）的敏感程度不如人类。中频灵敏度损失的来源被认为存在于耳膜和耳蜗毛细胞之间的某个地方。研究了频率和强度的差异阈值。它们是人类最小的。黑猩猩需要很长的反应时间来区分日语的合成元音[i]和[u]，以及[e]和[o]。黑猩猩根据第一个元音的频率来区分元音。这些结果得到了对同种元音样声音的感知的支持。讨论了w形灵敏度与元音感知之间的关系。对于辅音的感知，发音的方式是最重要的决定因素。对于顿音的感知，语音比位置特征更重要。黑猩猩和日本猴表现出声道正常化的能力和对顿音的分类感知能力。黑猩猩和日本猴并没有表现出右耳（左半球）在感知人类语言和同种声音方面的优势。研究人员将黑猩猩婴儿早期的声音发育与人类婴儿进行了比较。虽然黑猩猩宝宝会咕咕叫，但她并没有表现出咿呀学语的样子。这一结果表明了咿呀学语对人类语言发展的重要性。

The following four aspects of the vocal-auditory functions of the chimpanzee and the Japanese monkey were investigated : Basic auditory functions, the perception of human speech and conspecific vocal sounds, ear (hemisphere) dominance in the perception of speech and vocal sounds and early vocal development.The chimpanzee and the Japanese monkey showed a W-shaped auditory sensitivity function. Although they are more sensitive to high frequencies (higher than 8 kHz), they are less sensitive to low (lower than 250 Hz) and middle (2-6 kHz) frequencies than human. The origin(s) of the sensitivity loss at mid-frequencies were suggested to exist somewhere between the eardrum and hair cells in the cochlea. Difference thresholds for frequency and intensity were investigated. They were the smallest for human.The chimpanzee required long reaction times to discriminate between the synthetic Japanese vowels [i] and [u] and between [e] and [o]. The chimpanzee discriminates vowels based on the frequency of the first formant. These results were supported by the perception of conspecific vowel-like vocal sounds. The relation between the W-shaped sensitivity and the vowel perception was discussed. For the perception of consonants, the manner of articulation was the most important determinant. For the perception of stop consonants, the voicing was more important than the place feature. The chimpanzee and the Japanese monkey showed the ability of vocal tract normalization and the categorical perception of stop consonants.The chimpanzee and the Japanese monkey did not show the right ear (left hemisphere) dominance in the perception of human speech and conspecific vocal sounds. The early vocal development of a chimpanzee baby was compared with that of human babies. Although the chimpanzee baby had cooing, she did not show babbling. This result indicates the importance of babbling for the development of human speech.