Muluk Nuray Bayar, Yalçinkaya Fulya, Keith Robert W
Kirikkale University, ENT Department, Turkey.
Auris Nasus Larynx. 2011 Feb;38(1):6-13. doi: 10.1016/j.anl.2010.05.007.
The children with difficulty in receiving sounds presented at rapid rates in speech sounds and language learning period, may have delay in speech sounds and language development due to hearing speech sounds not clearly. Auditory temporal processing (ATP) is the ability to perceive auditory signals of brief duration accurately when presented at rapid rates. ATP can be evaluated by the random gap detection test (RGDT), which detects a brief gap between two stimuli. In this study, we investigated performance of children with previous language delay (PLD), currently having disorders in more than one speech sounds, on random gap detection test (RGDT) and RGDT-expanded (RGDT-EXP) tests.
12 children (8 male, 4 female) with previous language delay (PLD) and complaint of expressing speech sounds distorted, were included into the study. They had applied language training for at least one-year period in the past and in the current time, their language development is normal. They expressed one or more speech sounds as distorted. The control group consisted of 10 normal hearing children with normal phonological development and language matched for age; and who had not PLD (5 male, 5 female). Children language levels were evaluated by Preschool Language Scale-4 test; or Clinical evaluation of language fundamentals, fourth edition (CELF-4) according to child's age. Speech sounds development was assessed by Speech Sound Development Test (SSDT). They were applied RGDT and/if necessary, RGDT-EXP. Each child responded whether he/she heard one or two tones. Their responses were taken as verbally and/or hold up one finger or two fingers. In the second test, they were applied speech discrimination test in quiet environment and in noise. Gap detection thresholds (GDTs) were detected at 500-4000 Hz; and Composite GDTs (CGDTs) were found for the study and control groups. GDT/CGDT > 20 ms was considered as abnormal for temporal processing disorder.
In the study group with PLD, mean of the GDTs were all over the normal limits; and in control group, mean of GDTs were all in normal limits. The difference between the mean GDTs of the study group were significantly higher than the control groups at all frequencies of 500-4000 Hz. In PLD group, CGDT (103.53 ± 11.63 ms) was significantly higher than that of the control group, (10.35 ± 0.65 ms) (p=0.021).
The children with PLD have difficulties in perception of speech sounds at a certain rate, even they have not language learning difficulties. Therefore, difficulty in distinguishing of speech sounds may cause especially receptive language development delay. We believe that perception of the speech sounds and language in a certain speed; and temporally degraded speech programmes should be incorporated into the training programme and may help to prevent delays.
处于语音和语言学习阶段的儿童若难以接收快速呈现的语音，可能因无法清晰听到语音而出现语音和语言发育迟缓。听觉时间处理（ATP）是指在快速呈现时准确感知短暂听觉信号的能力。ATP可通过随机间隙检测测试（RGDT）进行评估，该测试可检测两个刺激之间的短暂间隙。在本研究中，我们调查了既往有语言发育迟缓（PLD）且目前存在一种以上语音障碍的儿童在随机间隙检测测试（RGDT）和扩展随机间隙检测测试（RGDT-EXP）中的表现。
12名既往有语言发育迟缓（PLD）且主诉语音表达失真的儿童（8名男性，4名女性）被纳入研究。他们过去至少接受了一年的语言训练，目前语言发育正常。他们表达的一个或多个语音存在失真。对照组由10名听力正常、语音发育正常且年龄匹配的儿童组成；且无PLD（5名男性，5名女性）。根据儿童年龄，通过《学前语言量表-4》测试或《语言基本能力临床评估第四版》（CELF-4）评估儿童的语言水平。通过语音发展测试（SSDT）评估语音发育情况。对他们进行RGDT测试，必要时进行RGDT-EXP测试。每个儿童回答他/她听到的是一个还是两个音调。他们的回答通过口头回答和/或举起一根或两根手指来表示。在第二项测试中，对他们进行安静环境和噪声环境下的语音辨别测试。在500-4000Hz检测间隙检测阈值（GDT）；并计算研究组和对照组的综合GDT（CGDT）。GDT/CGDT>20ms被认为是时间处理障碍异常。
在有PLD的研究组中，GDT的平均值均超出正常范围；而在对照组中，GDT的平均值均在正常范围内。在500-4000Hz的所有频率上，研究组的平均GDT与对照组之间的差异均显著高于对照组。在PLD组中，CGDT（103.53±11.63ms）显著高于对照组（10.35±0.65ms）（p=0.021）。
有PLD的儿童即使没有语言学习困难，在以一定速率感知语音方面也存在困难。因此，区分语音的困难可能尤其导致接受性语言发育迟缓。我们认为，以一定速度感知语音和语言；以及将时间上退化的语音程序纳入训练计划可能有助于预防发育迟缓。
