Institute of Cognitive Neuroscience, National Central University, No.300 Jhongda Rd., Jhongli County, Taoyuan City, 32001, Taiwan.
Psychon Bull Rev. 2019 Feb;26(1):250-260. doi: 10.3758/s13423-018-1513-y.
The ear and brain interact in an orchestrated manner to create sensations of phantom tones that are audible to listeners despite lacking physical presence in original sounds. The relative contribution of peripheral sensory cell activity and cortical mechanisms to phantom hearing remains elusive. The current study addressed the question of whether non-linear components of a complex signal exist that are not captured by the linear combination of cosines in a series. To this end, we investigated the source and spectro-temporal dynamics of non-linear components within two-tone complexes related to phantom acoustic perception. The empirical mode decomposition, a method for non-linear and non-stationary processes, was applied to extract the extra-aural existence of an oscillatory component within the original signal associated with the phantom sound. This travelling wave (phantom) has never before been observed in the sound's linear spectrum. We showed that the wave travels at a velocity that accurately maps onto the perceived phantom tone frequency. Phase coherence of oscillatory mode dynamics predicted discrimination sensitivity to phantom sounds by listeners. Perceived incidences of phantom tones correlated with magnitude of the Hilbert power spectra of the extra-aural component. Findings suggest a possible origin of phantom sounds that exists within the original signal, with potential implications for current models of non-linear cochlear mechanics and cortical dynamics in generating phantom percepts.
耳朵和大脑以协调的方式相互作用，产生听觉上可听的幻音，尽管原始声音中没有物理存在。外周感觉细胞活动和皮质机制对幻听的相对贡献仍然难以捉摸。本研究旨在探讨复杂信号中是否存在非线性成分，这些成分无法通过余弦级数的线性组合来捕捉。为此，我们研究了与幻听感知相关的双音复合体中非线性成分的来源和时频谱动态。经验模态分解是一种用于非线性和非平稳过程的方法，用于提取与幻声相关的原始信号中存在的振荡成分的耳外存在。这个行波（幻音）以前从未在声音的线性频谱中观察到过。我们表明，该波以与感知到的幻音频率精确对应的速度传播。振荡模式动力学的相位相干性预测了听众对幻声的辨别灵敏度。幻音的感知发生率与耳外成分的希尔伯特功率谱的幅度相关。研究结果表明，幻音可能存在于原始信号中，这可能对当前的非线性耳蜗力学模型和产生幻听知觉的皮质动力学模型产生影响。
