Warren J D, Jennings A R, Griffiths T D
Auditory Group, Medical School, University of Newcastle, Newcastle-upon-Tyne, NE2 4HH, UK.
Neuroimage. 2005 Feb 15;24(4):1052-7. doi: 10.1016/j.neuroimage.2004.10.031.
Spectral envelope is the shape of the power spectrum of sound. It is an important cue for the identification of sound sources such as voices or instruments, and particular classes of sounds such as vowels. In everyday life, sounds with similar spectral envelopes are perceived as similar: we recognize a voice or a vowel regardless of pitch and intensity variations, and we recognize the same vowel regardless of whether it is voiced (a spectral envelope applied to a harmonic series) or whispered (a spectral envelope applied to noise). In this functional magnetic resonance imaging (fMRI) experiment, we investigated the basis for analysis of spectral envelope by the human brain. Changing either the pitch or the spectral envelope of harmonic sounds produced similar activation within a bilateral network including Heschl's gyrus and adjacent cortical areas in the superior temporal lobe. Changing the spectral envelope of continuously alternating noise and harmonic sounds produced additional right-lateralized activation in superior temporal sulcus (STS). Our findings show that spectral shape is abstracted in superior temporal sulcus, suggesting that this region may have a generic role in the spectral analysis of sounds. These distinct levels of spectral analysis may represent early computational stages in a putative anteriorly directed stream for the categorization of sound.
频谱包络是声音功率谱的形状。它是识别声源（如声音或乐器）以及特定类别的声音（如元音）的重要线索。在日常生活中，具有相似频谱包络的声音被视为相似：无论音高和强度如何变化，我们都能识别出声音或元音；无论元音是有声的（应用于谐波序列的频谱包络）还是低语的（应用于噪声的频谱包络），我们都能识别出相同的元音。在这项功能磁共振成像（fMRI）实验中，我们研究了人类大脑分析频谱包络的基础。改变谐波声音的音高或频谱包络会在一个双侧网络中产生相似的激活，该网络包括颞上叶的赫氏回和相邻的皮质区域。改变连续交替的噪声和谐波声音的频谱包络会在颞上沟（STS）产生额外的右侧化激活。我们的研究结果表明，频谱形状在颞上沟被提取，这表明该区域可能在声音的频谱分析中具有一般作用。这些不同层次的频谱分析可能代表了一个假定的向前定向流中声音分类的早期计算阶段。
