Longitudinal observations of typical English voicing acquisition in a 2-year-old child: Stability of the contrast and considerations for clinical assessment

Early assessment of phonetic and phonological development requires knowledge of typical versus atypical speech patterns, as well as the range of individual developmental trajectories. The nature of data reporting in previous literature on typical voicing acquisition left aspects of the developmental process unclear and limited clinical applicability. This work extends a previous four-month group study to present data for one child over 12 months. Words containing initial /b p d t/ were elicited from a monolingual English-speaking 2-year-old child biweekly for 25 sessions. Voice onset time (VOT) was measured for each stop. For each consonant and recording session, we measured range as well as accuracy, overshoot and discreteness calculated for means and individual tokens. The results underscore the value of token-by-token analyses. They further reveal that typical development may involve an extended period of fluctuating voicing patterns, suggesting that the voiced/voiceless contrast may take months or years to stabilise.

对语音及音系发展开展早期评估，需掌握典型与非典型言语模式的差异，以及个体发育轨迹的分布范围。既往关于典型浊化习得的研究文献中，数据报告的方式未能阐明发育过程的部分环节，且临床应用价值受限。本研究在既往一项为期4个月的群组研究基础上进行拓展，呈现了一名单语英语母语的2岁儿童12个月内的相关数据。研究人员每两周对该儿童开展1次语音采集，共完成25次会话，采集了词首包含/b/、/p/、/d/、/t/的词汇。对每一个塞音辅音测量了嗓音起始时间（Voice Onset Time, VOT）。针对每个辅音及每一次录音会话，研究人员分别测量了其分布范围，以及基于均值与单个Token计算得到的准确率、超调量与离散程度。研究结果凸显了逐Token分析的重要价值。此外，研究还进一步揭示，典型语音发育可能会经历一段时长较长的浊音模式波动阶段，这表明清浊辅音对立的稳定可能需要数月乃至数年的时间。