University of North Carolina School of Medicine, Chapel Hill, USA.
J Speech Lang Hear Res. 2013 Feb;56(1):71-80. doi: 10.1044/1092-4388(2012/12-0008). Epub 2012 Aug 15.
Thresholds of school-aged children are elevated relative to those of adults for intensity discrimination and amplitude modulation (AM) detection. It is unclear how these findings are related or what role stimulus gating and dynamic envelope cues play in these results. Two experiments assessed the development of sensitivity to intensity increments in different stimulus contexts.
Thresholds for detecting an increment in level were estimated for normal-hearing children (5- to 10-year-olds) and adults. Experiment 1 compared intensity discrimination for gated and continuous presentation of a 1-kHz tone, with a 65-dB-SPL standard level. Experiment 2 compared increment detection and 16-Hz AM detection introduced into a continuous 1-kHz tone, with either 35- or 75-dB-SPL standard levels.
Children had higher thresholds than adults overall. All listeners were more sensitive to increments in the continuous than the gated stimulus and performed better at the 75- than at the 35-dB-SPL standard level. Both effects were comparable for children and adults. There was some evidence that children's AM detection was more adultlike than increment detection.
These results imply that memory for loudness across gated intervals is not responsible for children's poor performance but that multiple dynamic envelope cues may benefit children more than adults.
与成年人相比，学龄儿童在强度辨别和幅度调制（AM）检测方面的阈值较高。目前尚不清楚这些发现之间有何关系，以及刺激门控和动态包络线索在这些结果中扮演什么角色。两个实验评估了在不同刺激环境下对强度增量的敏感性的发展。
为正常听力的儿童（5 至 10 岁）和成年人估算了检测水平增量的阈值。实验 1 比较了门控和连续呈现 1 kHz 音调时的强度辨别，标准水平为 65 dB SPL。实验 2 比较了在连续 1 kHz 音调中引入的增量检测和 16 Hz AM 检测，标准水平分别为 35 或 75 dB SPL。
总体而言，儿童的阈值高于成年人。所有听众对连续刺激的增量都比门控刺激更敏感，在 75 dB SPL 的标准水平下的表现优于 35 dB SPL 的标准水平。这两个效果在儿童和成年人中都是可比的。有一些证据表明，儿童的 AM 检测比增量检测更成人化。
这些结果表明，门控间隔内响度的记忆并不是儿童表现不佳的原因，但多个动态包络线索可能使儿童比成年人受益更多。
