Human and Information Science Laboratory, NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Atsugi, Kanagawa, Japan.
PLoS One. 2010 Nov 8;5(11):e13866. doi: 10.1371/journal.pone.0013866.
There has been plentiful evidence of kinesthetically induced rapid compensation for unanticipated perturbation in speech articulatory movements. However, the role of auditory information in stabilizing articulation has been little studied except for the control of voice fundamental frequency, voice amplitude and vowel formant frequencies. Although the influence of auditory information on the articulatory control process is evident in unintended speech errors caused by delayed auditory feedback, the direct and immediate effect of auditory alteration on the movements of articulators has not been clarified.
METHODOLOGY/PRINCIPAL FINDINGS: This work examined whether temporal changes in the auditory feedback of bilabial plosives immediately affects the subsequent lip movement. We conducted experiments with an auditory feedback alteration system that enabled us to replace or block speech sounds in real time. Participants were asked to produce the syllable /pa/ repeatedly at a constant rate. During the repetition, normal auditory feedback was interrupted, and one of three pre-recorded syllables /pa/, /Φa/, or /pi/, spoken by the same participant, was presented once at a different timing from the anticipated production onset, while no feedback was presented for subsequent repetitions. Comparisons of the labial distance trajectories under altered and normal feedback conditions indicated that the movement quickened during the short period immediately after the alteration onset, when /pa/ was presented 50 ms before the expected timing. Such change was not significant under other feedback conditions we tested.
CONCLUSIONS/SIGNIFICANCE: The earlier articulation rapidly induced by the progressive auditory input suggests that a compensatory mechanism helps to maintain a constant speech rate by detecting errors between the internally predicted and actually provided auditory information associated with self movement. The timing- and context-dependent effects of feedback alteration suggest that the sensory error detection works in a temporally asymmetric window where acoustic features of the syllable to be produced may be coded.
已有大量证据表明，在言语发音运动中，动觉诱发的快速补偿可以应对意料之外的干扰。然而，除了控制基频、声幅和元音共振峰频率外，听觉信息在稳定发音方面的作用研究甚少。虽然在因听觉反馈延迟而导致的非意愿言语错误中，听觉信息对发音控制过程的影响显而易见，但听觉变化对发音器官运动的直接和即时影响尚未阐明。
方法/主要发现：本研究旨在探讨双唇爆破音的听觉反馈的时变是否会立即影响随后的唇运动。我们使用听觉反馈改变系统进行了实验，该系统可实时替换或阻断语音。要求参与者以恒定的速率重复发出 /pa/ 音节。在重复过程中，正常的听觉反馈被中断，参与者之前录制的三个音节中的一个 /pa/、/Φa/ 或 /pi/ 会在与预期产生起始时间不同的时间出现一次，而后续重复则不呈现任何反馈。在改变和正常反馈条件下的唇部距离轨迹比较表明，当 /pa/ 在预期时间提前 50 毫秒呈现时，在改变起始后的短暂时间内，运动速度加快。在我们测试的其他反馈条件下，这种变化不显著。
结论/意义：渐进听觉输入引起的早期发音表明，补偿机制通过检测与自身运动相关的内部预测和实际提供的听觉信息之间的误差，有助于通过听觉信息来维持恒定的语速。反馈改变的时间和上下文依赖性效应表明，感觉错误检测在一个时间不对称的窗口中起作用，在此窗口中可能会对要产生的音节的声学特征进行编码。
