Sheffield Sterling W, Haynes David S, Wanna George B, Labadie Robert F, Gifford René H
Department of Hearing and Speech Sciences, Vanderbilt University, Nashville, TN.
Department of Otolaryngology, Vanderbilt University, Nashville, TN.
J Am Acad Audiol. 2015 Mar;26(3):289-98. doi: 10.3766/jaaa.26.3.8.
Bilateral implant recipients theoretically have access to binaural cues. Research in postlingually deafened adults with cochlear implants (CIs) indicates minimal evidence for true binaural hearing. Congenitally deafened children who experience spatial hearing with bilateral CIs, however, might perceive binaural cues in the CI signal differently. There is limited research examining binaural hearing in children with CIs, and the few published studies are limited by the use of unrealistic speech stimuli and background noise.
The purposes of this study were to (1) replicate our previous study of binaural hearing in postlingually deafened adults with AzBio sentences in prelingually deafened children with the pediatric version of the AzBio sentences, and (2) replicate previous studies of binaural hearing in children with CIs using more open-set sentences and more realistic background noise (i.e., multitalker babble).
The study was a within-participant, repeated-measures design.
The study sample consisted of 14 children with bilateral CIs with at least 25 mo of listening experience.
Speech recognition was assessed using sentences presented in multitalker babble at a fixed signal-to-noise ratio. Test conditions included speech at 0° with noise presented at 0° (S0N0), on the side of the first CI (90° or 270°) (S0N1stCI), and on the side of the second CI (S0N2ndCI) as well as speech presented at 0° with noise presented semidiffusely from eight speakers at 45° intervals. Estimates of summation, head shadow, squelch, and spatial release from masking were calculated.
Results of test conditions commonly reported in the literature (S0N0, S0N1stCI, S0N2ndCI) are consistent with results from previous research in adults and children with bilateral CIs, showing minimal summation and squelch but typical head shadow and spatial release from masking. However, bilateral benefit over the better CI with speech at 0° was much larger with semidiffuse noise.
Congenitally deafened children with CIs have similar availability of binaural hearing cues to postlingually deafened adults with CIs within the same experimental design. It is possible that the use of realistic listening environments, such as semidiffuse background noise as in Experiment II, would reveal greater binaural hearing benefit for bilateral CI recipients. Future research is needed to determine whether (1) availability of binaural cues for children correlates with interaural time and level differences, (2) different listening environments are more sensitive to binaural hearing benefits, and (3) differences exist between pediatric bilateral recipients receiving implants in the same or sequential surgeries.
理论上，双侧植入者能够利用双耳线索。对语后聋成年人工耳蜗（CI）使用者的研究表明，几乎没有证据显示其具备真正的双耳听力。然而，通过双侧CI获得空间听力的先天性聋儿可能对CI信号中的双耳线索有不同的感知。关于CI儿童双耳听力的研究有限，少数已发表的研究因使用不切实际的言语刺激和背景噪声而受到限制。
本研究的目的是：（1）使用儿科版AzBio句子，在先天性聋儿中重复我们之前对语后聋成人使用AzBio句子进行双耳听力研究的结果；（2）使用更多的开放式句子和更逼真的背景噪声（即多说话者嘈杂声），重复之前对CI儿童双耳听力的研究。
本研究为受试者内重复测量设计。
研究样本包括14名双侧CI儿童，他们至少有25个月的听力经验。
在固定信噪比下，使用多说话者嘈杂声中呈现的句子评估言语识别。测试条件包括：言语在0°，噪声在0°呈现（S0N0）、在第一个CI一侧（90°或270°）（S0N1stCI）、在第二个CI一侧（S0N2ndCI），以及言语在0°，噪声从8个扬声器以45°间隔半扩散呈现。计算了总和、头影、静噪和掩蔽空间释放的估计值。
文献中常见的测试条件（S0N0、S0N1stCI、S0N2ndCI）的结果与之前对双侧CI成人和儿童的研究结果一致，显示总和和静噪最小，但头影和掩蔽空间释放典型。然而，在0°言语时，与较好的CI相比，半扩散噪声下的双侧获益要大得多。
在相同的实验设计中，先天性聋的CI儿童与语后聋的CI成人具有相似的双耳听力线索可用性。使用逼真的聆听环境，如实验II中的半扩散背景噪声，可能会使双侧CI使用者获得更大的双耳听力益处。未来需要开展研究以确定：（1）儿童双耳线索的可用性是否与双耳时间和水平差异相关；（2）不同的聆听环境对双耳听力益处是否更敏感；（3）在同期或分期手术中接受植入的儿科双侧使用者之间是否存在差异。
