ExpORL, Department of Neurosciences, K.U. Leuven, Leuven, Belgium.
Ear Hear. 2010 Oct;31(5):702-13. doi: 10.1097/AUD.0b013e3181e40dfe.
Several studies have demonstrated better speech perception performance in children using two rather than one cochlear implant (CI). The extent to which bilaterally implanted children benefit from binaural cues to segregate speech and noise in a spatial configuration is less clear. Although better-ear effects are expected to be similar to adults, it is unknown whether electrical stimulation allows true binaural processing of speech signals in noise. Moreover, little data are available on the binaural hearing abilities of normal-hearing children. This study aimed at (1) developing and evaluating a speech test based on numbers to determine speech reception thresholds (SRTs) fast and accurately in young children, (2) evaluating a setup for measuring benefits of speech perception in a spatial configuration in young children and determining normative values of normal-hearing children, and (3) measuring spatial speech benefits in cochlear-implanted children with good sound localization abilities.
The speech test was conducted using the Leuven Intelligibility Number Test (LINT) data base. The test was limited to the numbers 1 to 10 spoken by one female speaker ("LittleLINT"). The LINT speech-weighted noise was used as a masker. Perception of this speech material was evaluated at fixed signal-to-noise ratios (SNRs) through monaural presentation via headphones in 34 normal-hearing children of 4 and 5 yrs of age and 20 normal-hearing adults. Subsequently, spatial speech perception benefits were measured in 50 normal-hearing children between 4 and 8 yrs of age, 15 normal-hearing adults, and eight children with bilateral CIs. An adaptive procedure was used for estimating unilateral and bilateral SRTs for different spatial configurations of speech and noise. Speech was always presented at 0 degrees azimuth (the front) and noise at the front, 90 degrees to the right, or 90 degrees to the left.
Unilateral headphone SRTs for the LittleLINT were higher for children (-9 dB SNR) than for adults (-13 dB SNR) and were lower than those for the LINT (-10 dB SNR for adults). Slopes (12 to 14%/dB) were comparable with that of the LINT (15%/dB), suggesting equal efficiency for the limited set of numbers. Normal-hearing subjects demonstrated several benefits of two-ear listening in spatial configurations (spatial release from masking [SRM], head shadow, summation, and squelch). Only SRM was influenced by age. Implanted children clearly benefited from bilateral implantation, as shown by SRM (3 dB) and head shadow effects (4 to 6 dB) comparable with normal-hearing children, but no summation or binaural squelch was established. The first CI seemed to contribute most to spatial speech perception.
The steep slope, the familiarity to children, and the repeatability of lists make the LittleLINT suitable for fast and accurate SRT estimation in children. Spatial speech perception benefits were observed in normal-hearing subjects from the age of 4 yrs. Cochlear-implanted children showed better-ear effects but there was no evidence of true binaural processing.
多项研究表明，在儿童中使用两个而不是一个人工耳蜗（CI）可以获得更好的语音感知表现。双侧植入儿童在空间配置中利用双耳线索来分离语音和噪声的程度尚不清楚。尽管预计更好耳的效果与成人相似，但尚不清楚电刺激是否允许在噪声中对语音信号进行真正的双耳处理。此外，关于正常听力儿童的双耳听力能力的数据很少。本研究旨在：（1）开发和评估一种基于数字的语音测试，以快速准确地确定幼儿的语音接收阈值（SRT）；（2）评估一种用于测量幼儿空间感知益处的设置，并确定正常听力儿童的正常值；（3）测量具有良好声音定位能力的人工耳蜗植入儿童的空间语音益处。
语音测试使用鲁汶可理解度数字测试（LINT）数据库进行。测试仅限于一位女性说话者（“LittleLINT”）说出的数字 1 到 10。LINT 语音加权噪声用作掩蔽器。通过耳机在 34 名 4 岁和 5 岁的正常听力儿童和 20 名正常听力成人中以固定信噪比（SNR）评估对这种语音材料的感知。随后，在 50 名 4 至 8 岁的正常听力儿童、15 名正常听力成人和 8 名双侧人工耳蜗植入儿童中测量空间语音感知益处。使用自适应程序来估计不同的语音和噪声空间配置的单侧和双侧 SRT。语音始终在 0 度方位（正面）和噪声在正面、90 度右侧或 90 度左侧呈现。
LittleLINT 的单侧耳机 SRT 对于儿童（-9 dB SNR）高于成人（-13 dB SNR），并且低于 LINT（成人-10 dB SNR）。斜率（12%至 14%/dB）与 LINT（15%/dB）相当，表明有限数量的数字效率相等。正常听力受试者在空间配置中表现出双耳聆听的多种益处（空间掩蔽释放[SRM]、头影、总和和抑制）。只有 SRM 受年龄影响。植入儿童表现出双侧植入的明显益处，如 SRM（3 dB）和头影效应（4 至 6 dB）与正常听力儿童相当，但未建立总和或双耳抑制。第一台人工耳蜗似乎对空间语音感知的贡献最大。
陡峭的斜率、儿童的熟悉程度和列表的可重复性使 LittleLINT 适合儿童快速准确的 SRT 估计。从 4 岁开始，正常听力受试者就观察到了空间语音感知的益处。人工耳蜗植入儿童表现出更好的听力效果，但没有证据表明存在真正的双耳处理。
