Cranen B, Boves L
J Acoust Soc Am. 1987 Mar;81(3):734-46. doi: 10.1121/1.394842.
When subglottal pressure signals which are recorded during normal speech production are spectrally analyzed, the frequency of the first spectral maximum appears to deviate appreciably from the first resonance frequency which has been reported in the literature and which stems from measurements of the acoustic impedance of the subglottal system. It is postulated that this is caused by the spectrum of the excitation function. This hypothesis is corroborated by a modeling study. Using an extended version of the well-known two-mass model of the vocal folds that can account for a glottal leak, it is shown that under realistic physiological assumptions glottal flow waveforms are generated whose spectral properties cause a downward shift of the location of the first spectral maximum in the subglottal pressure signals. The order of magnitude of this effect is investigated for different glottal settings and with a subglottal system that is modeled according to the impedance measurements reported in the literature. The outcomes of this modeling study show that the location of the first spectral maximum of the subglottal pressure may deviate appreciably from the natural frequency of the subglottal system. As a consequence, however, the comfortable assumption that in normal speech the glottal excitation function is constant and zero during the "closed glottis interval" has to be called into question.
当对正常言语产生过程中记录的声门下压力信号进行频谱分析时，第一个频谱峰值的频率似乎明显偏离文献中报道的、源于声门下系统声阻抗测量的第一共振频率。据推测，这是由激励函数的频谱引起的。这一假设得到了一项建模研究的证实。使用一个扩展版的、能够考虑声门漏气情况的著名声带双质量模型，研究表明，在现实的生理假设下，所产生的声门气流波形的频谱特性会导致声门下压力信号中第一个频谱峰值的位置向下偏移。针对不同的声门设置以及根据文献中报道的阻抗测量结果建模的声门下系统，研究了这种效应的量级。这项建模研究的结果表明，声门下压力的第一个频谱峰值的位置可能明显偏离声门下系统的固有频率。然而，由此带来的结果是，在正常言语中声门激励函数在“声门关闭间隔”期间是恒定且为零的这一令人满意的假设不得不受到质疑。
