Speech envelope following responses in children (Easwar et al., 2022)

<strong>Purpose:</strong> Envelope following responses (EFRs) could be useful for objectively evaluating audibility of speech in children who are unable to participate in routine clinical tests. However, relative to adults, the characteristics of EFRs elicited by frequency-specific speech and their utility in predicting audibility in children are unknown. <strong>Method: </strong>EFRs were elicited by the first (F1) and second and higher formants (F2+) of male-spoken vowels /u/ and /i/ and by fricatives /ʃ/ and /s/ in the token /suʃi/ presented at 15, 35, 55, 65, and 75 dB SPL. The F1, F2+, and fricatives were low-, mid-, and high-frequency dominant, respectively. EFRs were recorded between the vertex and the nape from twenty-three 6- to 17-year-old children and 21 young adults with normal hearing. Sensation levels of stimuli were estimated based on behavioral thresholds. <strong>Results:</strong> In children, amplitude decreased with age for /ʃ/-elicited EFRs but remained stable for low- and mid-frequency stimuli. As a group, EFR amplitude and phase coherence did not differ from that of adults. EFR sensitivity (proportion of audible stimuli detected) and specificity (proportion of inaudible stimuli not detected) did not vary between children and adults. Consistent with previous work, EFR sensitivity increased with stimulus frequency and level. The type of statistical indicator used for EFR detection did not influence accuracy in children. <strong>Conclusions:</strong> Adultlike EFRs in 6- to 17-year-old typically developing children suggest mature envelope encoding for low- and mid-frequency stimuli. EFR sensitivity and specificity in children, when considering a wide range of stimulus levels and audibility, are ~77% and ~92%, respectively. <br> <strong>Supplemental Material S1. </strong>EFR sensitivity (Table 1A) and specificity (Table 1B) at each level for each stimulus and statistical indicator in children and adults. <br> Easwar, V., Purcell, D., Lasarev, M., McGrath, E., &amp; Galloy, M. (2022). Speech-evoked envelope following responses in children and adults. <em>Journal of Speech, Language, and Hearing Research.</em> Advance online publication. https://doi.org/10.1044/2022_JSLHR-22-00156

研究目的：包络跟随反应（Envelope Following Responses, EFRs）可用于对无法配合常规临床测试的儿童的言语可听度进行客观评估。然而，相较于成人，由频率特异性言语诱发的EFR的特征，以及其在预测儿童言语可听度中的应用价值，目前仍不明确。
研究方法：本研究以男性发音的元音/u/与/i/的第一共振峰（F1）、第二及以上共振峰（F2+），以及语音片段/suʃi/中的擦音/ʃ/与/s/作为刺激材料，以15、35、55、65、75 dB声压级（dB SPL）呈现，诱发包络跟随反应。其中，F1、F2+与擦音分别对应低频主导、中频主导与高频主导的刺激。本研究从23名6至17岁儿童以及21名听力正常的青年成人的颅顶点与颈后之间记录EFR，刺激的感觉级基于行为听阈进行估算。
研究结果：在儿童群体中，/ʃ/诱发的EFR幅值随年龄增长而降低，但低频与中频刺激诱发的EFR幅值保持稳定。整体而言，儿童与成人的EFR幅值与相位相干性无显著差异。EFR敏感度（可听刺激被检出的比例）与特异度（不可听刺激未被检出的比例）在儿童与成人之间无明显变化。与既往研究结果一致，EFR敏感度随刺激频率与刺激强度的升高而提升。用于EFR检测的统计指标类型，不会影响儿童群体的检测准确性。
研究结论：6至17岁典型发育儿童的EFR特征与成人相似，表明其对低频与中频刺激的包络编码已发育成熟。在涵盖广泛刺激强度与可听度范围的情况下，儿童的EFR敏感度与特异度分别约为77%与92%。
补充材料S1：儿童与成人中各刺激、各统计指标在各刺激强度下的EFR敏感度（表1A）与特异度（表1B）。
参考文献：Easwar, V., Purcell, D., Lasarev, M., McGrath, E., & Galloy, M. (2022). 儿童与成人的言语诱发包络跟随反应. 《言语、语言与听力研究杂志》. 在线优先出版. https://doi.org/10.1044/2022_JSLHR-22-00156