Department of Psychology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
Adv Exp Med Biol. 2013;787:137-45. doi: 10.1007/978-1-4614-1590-9_16.
High-frequency pure tones (>6 kHz), which alone do not produce salient melodic pitch information, provide melodic pitch information when they form part of a harmonic complex tone with a lower fundamental frequency (F0). We explored this phenomenon in normal-hearing listeners by measuring F0 difference limens (F0DLs) for harmonic complex tones and pure-tone frequency difference limens (FDLs) for each of the tones within the harmonic complexes. Two spectral regions were tested. The low- and high-frequency band-pass regions comprised harmonics 6-11 of a 280- or 1,400-Hz F0, respectively; thus, for the high-frequency region, audible frequencies present were all above 7 kHz. Frequency discrimination of inharmonic log-spaced tone complexes was also tested in control conditions. All tones were presented in a background of noise to limit the detection of distortion products. As found in previous studies, F0DLs in the low region were typically no better than the FDL for each of the constituent pure tones. In contrast, F0DLs for the high-region complex were considerably better than the FDLs found for most of the constituent (high-frequency) pure tones. The data were compared with models of optimal spectral integration of information, to assess the relative influence of peripheral and more central noise in limiting performance. The results demonstrate a dissociation in the way pitch information is integrated at low and high frequencies and provide new challenges and constraints in the search for the underlying neural mechanisms of pitch.
高频纯音（>6 kHz）本身不产生明显的旋律音高信息，但当它们与低频基频（F0）的谐波复合音形成一部分时，会提供旋律音高信息。我们通过测量谐波复合音的 F0 差阈（F0DL）和复合音中每个纯音的纯音频率差阈（FDL），来研究正常听力听众中的这种现象。测试了两个频谱区域。低频和高频带通区域分别包含 280 或 1400 Hz F0 的第 6-11 个谐波；因此，对于高频区域，可听频率均高于 7 kHz。在对照条件下，还测试了非谐波对数间隔音复合音的频率辨别力。所有音均在噪声背景下呈现，以限制对失真产物的检测。如先前研究所示，低频区域的 F0DL 通常不如每个组成纯音的 FDL。相比之下，高频区域复合音的 F0DL 明显优于大多数组成（高频）纯音的 FDL。将数据与信息的最佳频谱整合模型进行比较，以评估外周和更中心噪声对限制性能的相对影响。结果表明，在低频和高频处，音高信息的整合方式存在差异，为寻找音高的潜在神经机制提供了新的挑战和限制。
