Shofner William P, Whitmer William M, Yost William A
Parmly Hearing Institute, Loyola University Chicago, Chicago, Illinois 60626, USA.
J Acoust Soc Am. 2005 Nov;118(5):3187-97. doi: 10.1121/1.2049107.
Behavioral responses obtained from chinchillas trained to discriminate a cosine-phase harmonic tone complex from wideband noise indicate that the perception of 'pitch' strength in chinchillas is largely influenced by periodicity information in the stimulus envelope. The perception of 'pitch' strength was examined in chinchillas in a stimulus generalization paradigm after animals had been retrained to discriminate infinitely iterated rippled noise from wideband noise. Retrained chinchillas gave larger behavioral responses to test stimuli having strong fine structure periodicity, but weak envelope periodicity. That is, chinchillas learn to use the information in the fine structure and consequently, their perception of 'pitch' strength is altered. Behavioral responses to rippled noises having similar periodicity strengths, but large spectral differences were also tested. Responses to these rippled noises were similar, suggesting a temporal analysis can be used to account for the behavior. Animals were then retested using the cosine-phase harmonic tone complex as the expected signal stimulus. Generalization gradients returned to those obtained originally in the naïve condition, suggesting that chinchillas do not remain "fine structure listeners," but rather revert back to being "envelope listeners" when the periodicity strength in the envelope of the expected stimulus is high.
从经过训练以区分余弦相位谐波音调复合体与宽带噪声的毛丝鼠身上获得的行为反应表明，毛丝鼠对“音高”强度的感知在很大程度上受刺激包络中的周期性信息影响。在动物重新接受训练以区分无限迭代的波纹噪声与宽带噪声后，在刺激泛化范式中对毛丝鼠的“音高”强度感知进行了检查。重新训练后的毛丝鼠对具有强精细结构周期性但弱包络周期性的测试刺激给出了更大的行为反应。也就是说，毛丝鼠学会了利用精细结构中的信息，因此它们对“音高”强度的感知发生了改变。还测试了对具有相似周期性强度但光谱差异较大的波纹噪声的行为反应。对这些波纹噪声的反应相似，表明可以使用时间分析来解释这种行为。然后使用余弦相位谐波音调复合体作为预期信号刺激对动物进行重新测试。泛化梯度恢复到最初在未训练状态下获得的水平，这表明当预期刺激的包络中的周期性强度较高时，毛丝鼠不会一直是“精细结构聆听者”，而是会恢复为“包络聆听者”。
