Purpose The current study examines the pattern of misidentified vowels produced by individuals with dysarthria secondary to amyotrophic lateral sclerosis (ALS). Method Twenty-three individuals with ALS and 22 typical individuals produced 10 monophthongs in an /h/-vowel-/d/ context. One hundred thirty-five listeners completed a forced-choice vowel identification test. Misidentified vowels were examined in terms of the target vowel categories (front–back; low–mid–high) and the direction of misidentification (the directional pattern when the target vowel was misidentified, e.g., misidentification “to a lower vowel”). In addition, acoustic predictors of vowel misidentifications were tested based on log first formant (F1), log second formant, log F1 vowel inherent spectral change, log second formant vowel inherent spectral change, and vowel duration. Results First, high and mid vowels were more frequently misidentified than low vowels for all speaker groups. Second, front and back vowels were misidentified at a similar rate for both the Mild and Severe groups, whereas back vowels were more frequently misidentified than front vowels in typical individuals. Regarding the direction of vowel misidentification, vowel errors were mostly made within the same backness (front–back) category for all groups. In addition, more errors were found toward a lower vowel category than toward a higher vowel category in the Severe group, but not in the Mild group. Overall, log F1 difference was identified as a consistent acoustic predictor of the main vowel misidentification pattern. Conclusion Frequent misidentifications in the vowel height dimension and the acoustic predictor, F1, suggest that limited tongue height control is the major articulatory dysfunction in individuals with ALS. Clinical implications regarding this finding are discussed.

中文翻译：

---

继发于肌萎缩侧索硬化症的构音障碍患者的元音误认模式

目的目前的研究调查了继发于肌萎缩侧索硬化症 (ALS) 的构音障碍患者产生的误认元音的模式。 方法23 名 ALS 患者和 22 名典型患者在 /h/-元音-/d/ 语境中发出了 10 个单音。一百三十五名听众完成了强制选择元音识别测试。根据目标元音类别（前-后；低-中-高）和误识别方向（目标元音被误识别时的方向模式，例如误识别“低元音”）来检查误识别的元音。此外，还根据对数第一共振峰 (F1)、对数第二共振峰、对数 F1 元音固有频谱变化、对数第二共振峰元音固有频谱变化和元音持续时间，测试了元音误识别的声学预测器。 结果首先，对于所有说话者群体来说，高元音和中元音比低元音更容易被错误识别。其次，轻度组和重度组的前元音和后元音被错误识别的比率相似，而典型个体中后元音比前元音更容易被错误识别。关于元音错误识别的方向，所有组的元音错误大多发生在同一后置（前-后）类别内。此外，在严重组中，低元音类别的错误比高元音类别的错误更多，但在轻度组中则不然。总体而言，log F1 差异被认为是主要元音错误识别模式的一致声学预测因子。 结论元音高度维度和声学预测因子 F1 的频繁误判表明有限的舌头高度控制是 ALS 患者的主要发音功能障碍。讨论了这一发现的临床意义。