Department of Physical Medicine & Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
Department of Speech, Language and Hearing Sciences, Moody College of Communication, The University of Texas at Austin, Austin, Texas.
J Voice. 2024 Jan;38(1):1-9. doi: 10.1016/j.jvoice.2021.08.004. Epub 2021 Oct 12.
Vocal vibrato is a singing technique that involves periodic modulation of fundamental frequency (f) and intensity. The physiological sources of modulation within the speech mechanism and the interactions between the laryngeal source and vocal tract filter in vibrato are not fully understood. Therefore, the purpose of this study was to determine if differences in the rate and extent of f and intensity modulation could be captured using simultaneously recorded signals from a neck-surface vibration sensor and a microphone, which represent features of the source before and after supraglottal vocal tract filtering.
Nine classically-trained singers produced sustained vowels with vibrato while simultaneous signals were recorded using a vibration sensor and a microphone. Acoustical analyses were performed to measure the rate and extent of f and intensity modulation for each trial. Paired-samples sign tests were used to analyze differences between the rate and extent of f and intensity modulation in the vibration sensor and microphone signals.
The rate and extent of f modulation and the extent of intensity modulation were equivalent in the vibration sensor and microphone signals, but the rate of intensity modulation was significantly higher in the microphone signal than in the vibration sensor signal. Larger differences in the rate of intensity modulation were seen with vowels that typically have smaller differences between the first and second formant frequencies.
This study demonstrated that the rate of intensity modulation at the source prior to supraglottal vocal tract filtering, as measured in neck-surface vibration sensor signals, was lower than the rate of intensity modulation after supraglottal vocal tract filtering, as measured in microphone signals. The difference in rate varied based on the vowel. These findings provide further support of the resonance-harmonics interaction in vocal vibrato. Further investigation is warranted to determine if differences in the physiological source(s) of vibrato account for inconsistent relationships between the extent of intensity modulation in neck-surface vibration sensor and microphone signals.
声乐颤音是一种涉及基频（f）和强度周期性调制的歌唱技巧。语音机制中调制的生理来源以及声带源与颤音声道滤波器之间的相互作用尚未完全理解。因此，本研究的目的是确定是否可以使用颈表面振动传感器和麦克风同时记录的信号来捕获 f 和强度调制的速率和幅度的差异，这些信号分别代表声道滤波前和声道滤波后的源的特征。
9 位受过古典训练的歌手在产生带有颤音的持续元音时，同时使用振动传感器和麦克风记录信号。进行声学分析以测量每个试验中 f 和强度调制的速率和幅度。采用配对样本符号检验分析振动传感器和麦克风信号中 f 和强度调制的速率和幅度的差异。
f 调制的速率和幅度以及强度调制的幅度在振动传感器和麦克风信号中是等效的，但强度调制的速率在麦克风信号中明显高于振动传感器信号。在第一和第二共振峰频率之间差异通常较小的元音中，强度调制的速率差异更大。
本研究表明，在经过声道滤波之前，通过颈表面振动传感器信号测量的源处的强度调制的速率低于在经过声道滤波之后，通过麦克风信号测量的强度调制的速率。速率差异基于元音而变化。这些发现为共振-谐波相互作用在声乐颤音中的作用提供了进一步的支持。进一步的研究需要确定颤音的生理来源的差异是否解释了颈表面振动传感器和麦克风信号中强度调制幅度之间不一致的关系。
