Wang Xin, Humes Larry E
Department of Speech and Hearing Sciences, Indiana University, Bloomington, Indiana 47405-7002, USA.
Ear Hear. 2008 Oct;29(5):725-45. doi: 10.1097/AUD.0b013e31817bdd42.
The purpose of this study was to investigate how young normal-hearing (YNH) and elderly hearing-impaired (EHI) listeners make use of redundant speech-like cues when classifying nonspeech sounds having multiple stimulus dimensions.
A total of four experiments were conducted with 10 to 12 listeners per group in each experiment. There were 27 stimuli, making use of all possible combinations of three stimulus values along each of three cue dimensions. Stimuli were comprised of two brief sequential noise bursts separated by a temporal gap. Stimulus dimensions were: (1) the center frequency of the noise bursts; (2) the duration of the temporal gap separating the noise bursts; and (3) the direction of a frequency transition in the second noise burst.
Experiment 1 verified that the stimulus values selected resulted in adjacent steps along each stimulus being easily discriminable [(P(c) > or = 90%]). In experiment 2, similarity judgments were obtained for all possible pairs of the 27 stimuli. Multidimensional scaling confirmed that the three acoustic dimensions existed as separate dimensions perceptually. In experiment 3, listeners were then trained to classify three exemplar stimuli. After the training, they were required to classify all 27 stimuli and these results led to the derivation of attentional weights for each stimulus dimension. Both groups focused their attention on the frequency-transition dimension during the classification task. Finally, experiment 4 demonstrated that the attentional weights derived in experiment 3 were reliable and that both EHI and YNH participants could be trained to shift their attention to a cue dimension (temporal-gap) not preferred in experiment 3, although older adults required much more training to achieve this shift in attention.
For the speech-like, multidimensional acoustic stimuli used here, YNH and EHI listeners attended to the same dimensions of the stimuli when classifying them. In general, the EHI listeners required more time to acquire the ability to categorize the stimuli, and to change their focus to alternate stimulus dimensions.
本研究旨在调查年轻听力正常（YNH）和老年听力受损（EHI）的听众在对具有多个刺激维度的非语音声音进行分类时如何利用冗余的语音样线索。
每组10至12名听众，共进行了四项实验。有27种刺激，利用了三个线索维度中每个维度上三个刺激值的所有可能组合。刺激由两个短暂的连续噪声脉冲组成，中间有一个时间间隔。刺激维度为：（1）噪声脉冲的中心频率；（2）分隔噪声脉冲的时间间隔的持续时间；（3）第二个噪声脉冲中的频率转换方向。
实验1证实所选的刺激值导致每个刺激的相邻步长易于区分[P(c)≥90%]。在实验2中，获得了27种刺激中所有可能对的相似性判断。多维标度证实这三个声学维度在感知上是作为独立维度存在的。在实验3中，然后训练听众对三个示例刺激进行分类。训练后，要求他们对所有27种刺激进行分类，这些结果导致得出每个刺激维度的注意力权重。两组在分类任务中都将注意力集中在频率转换维度上。最后，实验4表明实验3中得出的注意力权重是可靠的，并且EHI和YNH参与者都可以通过训练将注意力转移到实验3中不偏好的线索维度（时间间隔）上，尽管老年人需要更多的训练才能实现这种注意力转移。
对于此处使用的语音样多维声学刺激，YNH和EHI听众在对其进行分类时关注刺激的相同维度。一般来说，EHI听众需要更多时间来获得对刺激进行分类的能力，并将注意力转移到其他刺激维度上。
