Clear speech refers to intentionally modifying conversational speech to maximise intelligibility. This study aimed to compare the speech behaviour of patients with progressive supranuclear palsy (PSP), multiple system atrophy (MSA) and Parkinson's disease (PD) under conversational and clear speech conditions to gain greater pathophysiological insight. A total of 68 participants including 17 PD, 17 MSA, 17 PSP and 17 healthy controls (HC) performed two readings of the same standardized passage. During the first reading, participants were instructed to read the text in an ordinary way, while during the second reading to read the text as clearly as possible. Acoustic analyses were based upon measurements of mean loudness, loudness variability, pitch variability, vowel articulation, articulation rate and speech severity. During clear speech production, PD patients were able to achieve improvements mainly in loudness (p < 0.05) and pitch variability (p < 0.001), leading to a reduction in overall speech severity (p < 0.001), whereas PSP and MSA patients were able to modulate only articulation rate (p < 0.05). Contrary to HC and PD groups, which slowed or maintained articulation rate, PSP and MSA groups employed a markedly faster articulation rate under the clear speech condition indicating an opposing approach to speech adaptation. Patients with atypical Parkinsonism showed a different strategy to intentionally improve their speech performance following a simple request to produce speech more clearly compared to PD, suggesting important therapeutic implications for speech rehabilitation management.

清晰的语音是指有意修改会话语音以最大限度地提高可懂度。本研究旨在比较进行性核上性麻痹 (PSP)、多系统萎缩 (MSA) 和帕金森病 (PD) 患者在会话和清晰语音条件下的言语行为，以获得更深入的病理生理学见解。包括 17 名 PD、17 名 MSA、17 名 PSP 和 17 名健康对照 (HC) 在内的 68 名参与者对同一标准化段落进行了两次阅读。在第一次阅读时，要求参与者以普通方式阅读文本，而在第二次阅读时，要求参与者尽可能清楚地阅读文本。声学分析基于对平均响度、响度可变性、音高可变性、元音清晰度、清晰度和语音严重性的测量。p  < 0.05) 和音高变异性 ( p  < 0.001)，导致整体语音严重性降低 ( p  < 0.001)，而 PSP 和 MSA 患者只能调节发音速度 ( p  < 0.05)。与 HC 和 PD 组减慢或保持发音速度相反，PSP 和 MSA 组在清晰的语音条件下采用明显更快的发音速度，表明语音适应的相反方法。与 PD 相比，非典型帕金森病患者表现出一种不同的策略，在提出更清晰的语音的简单要求后有意提高他们的言语能力，这表明对言语康复管理具有重要的治疗意义。