Sakayori Shuichi, Kitama Toshihiro, Chimoto Sohei, Qin Ling, Sato Yu
Department of Physiology, Yamanashi Medical University, Tamaho, Japan.
Neurosci Res. 2002 Jun;43(2):155-62. doi: 10.1016/s0168-0102(02)00026-3.
The first two formant frequencies (F1 and F2) are the cues important for vowel identification. In the categorization of the naturally spoken vowels, however, there are overlaps among the vowels in the F1 and F2 plane. The fundamental frequency (F0), the third formant frequency (F3) and the spectral envelope have been proposed as additional cues. In the present study, to investigate the spectral regions essential for the vowel identification, untrained subjects performed the forced-choice identification task in response to Japanese isolated vowels (/a, o, u, e, i/), in which some spectral regions were deleted. Minimum spectral regions needed for correct vowel identification were the two regions including F1 and F2 (the first and fourth in the quadrisected F1-F2 regions in Bark scale). This was true even when phonetically different vowels had a similar combination of F1 and F2 frequency components. F0 and F3 cues were not necessarily needed. It is concluded that the relative importance in the spectral region is not equivalent, but weighted on the two critical spectral regions. The auditory system may identify the vowels by analyzing the information of the spectral shapes and the formant frequencies (F1 and F2) in these critical spectral regions.
前两个共振峰频率（F1和F2）是用于元音识别的重要线索。然而，在自然语音元音的分类中，元音在F1和F2平面上存在重叠。基频（F0）、第三共振峰频率（F3）和频谱包络已被提议作为额外的线索。在本研究中，为了探究对于元音识别至关重要的频谱区域，未经训练的受试者针对日语孤立元音（/a、o、u、e、i/）执行了强制选择识别任务，其中一些频谱区域被删除。正确识别元音所需的最小频谱区域是包括F1和F2的两个区域（在巴克标度中F1 - F2四等分区域中的第一和第四区域）。即使语音上不同的元音具有相似的F1和F2频率成分组合，情况也是如此。F0和F3线索不一定是必需的。得出的结论是，频谱区域中的相对重要性并不等同，而是在这两个关键频谱区域上有加权。听觉系统可能通过分析这些关键频谱区域中的频谱形状信息和共振峰频率（F1和F2）来识别元音。
