Merrikhi Yaser, Parsa Mohsen, Daliri Ayoub
College of Health Solutions, Arizona State University, Tempe.
J Speech Lang Hear Res. 2025 Aug 12;68(8):3748-3758. doi: 10.1044/2025_JSLHR-24-00572. Epub 2025 Jun 30.
The brain relies on feedforward and feedback control systems to produce speech movements. Both control systems use auditory errors to generate responses that ensure the accuracy of speech movements. Traditionally, separate auditory perturbation paradigms are used to examine these control systems in isolation; however, this conventional practice is time-consuming and poses practical challenges. This study aimed to develop a new paradigm to examine both control systems concurrently.
We applied different auditory perturbation magnitudes (0, 125, 250, and 500 Hz) and directions (ε-to-ɪ and ε-to-ӕ) that randomly changed every six trials. We measured formant changes during early (0-100 ms) and late (200-300 ms) time points of production. Early response was used to calculate adaptive responses (a measure of the feedforward control system). The difference between late and early responses was used to calculate corrective responses (a measure of the feedback control system).
We found that participants produced (a) adaptive and corrective responses in the opposite direction of the perturbation direction and (b) proportionally larger adaptive and corrective responses to the smallest perturbation in the ε-to-ɪ direction. Additionally, participants who responded more to ε-to-ɪ perturbations also responded more to ε-to-ӕ perturbations.
These findings suggest that (a) the brain may have similar error sensitivity in the ε-to-ɪ and ε-to-ӕ directions and considers error magnitudes in preparing its responses to errors, and (b) our proposed paradigm is a promising approach to efficiently and concurrently measure the contributions of the feedback and feedforward controls systems.
大脑依靠前馈和反馈控制系统来产生言语运动。这两种控制系统都利用听觉误差来生成确保言语运动准确性的反应。传统上，使用单独的听觉扰动范式来分别研究这些控制系统；然而，这种传统做法既耗时又带来实际挑战。本研究旨在开发一种新的范式，以同时研究这两种控制系统。
我们应用了不同的听觉扰动幅度（0、125、250和500赫兹）和方向（ε到ɪ以及ε到ӕ），每六次试验随机变化一次。我们在发声的早期（0 - 100毫秒）和晚期（200 - 300毫秒）时间点测量共振峰变化。早期反应用于计算适应性反应（前馈控制系统的一种度量）。晚期和早期反应之间的差异用于计算校正反应（反馈控制系统的一种度量）。
我们发现，参与者产生了（a）与扰动方向相反的适应性和校正反应，以及（b）在ε到ɪ方向上对最小扰动产生比例更大的适应性和校正反应。此外，对ε到ɪ扰动反应更大的参与者对ε到ӕ扰动的反应也更大。
这些发现表明，（a）大脑在ε到ɪ和ε到ӕ方向上可能具有相似的误差敏感性，并在准备对误差的反应时考虑误差大小，以及（b）我们提出的范式是一种有前景的方法，可有效且同时测量反馈和前馈控制系统的贡献。
