Fay Richard R
Parmly Hearing Institute, Loyola University Chicago, Chicago, Illinois 60626, USA.
J Acoust Soc Am. 2009 Jun;125(6):4053-9. doi: 10.1121/1.3124777.
The perception of two simultaneous tones was investigated in goldfish using classical respiratory conditioning and a stimulus generalization paradigm. Pairs of tones were used to make up a mixture of 150 Hz and a higher harmonic or a mistuned harmonic. Fish were conditioned to the two-tone mixture and then tested for generalization to several pure tones. The simultaneous tones tended to be segregated in perception, with the generalization gradient for single tones having two peaks corresponding to the frequencies of the tone pairs. There were no consistent differences in the generalization gradients following conditioning to harmonic or inharmonic tone pairs. In addition, experiments were carried out in which the two tones of the pair were heard on alternate trials, always as single tones, followed by generalization tests to single tones. There was more generalization in this experiment, reflecting the fact that conditioning and generalization test stimuli were both single tones. However, the shapes of the generalization gradients were similar to those in which fish were conditioned to two simultaneous tones, indicating that the simultaneity of the tones did not make them harder to segregate. As the frequency separation between the two components narrowed, segregation tended to fail.
利用经典呼吸条件反射和刺激泛化范式，在金鱼身上研究了对两个同时出现的音调的感知。成对的音调用于构成150赫兹与更高谐波或失谐谐波的混合音。使金鱼适应这种双音调混合物，然后测试其对几种纯音的泛化能力。同时出现的音调在感知上倾向于被分离，单音的泛化梯度有两个峰值，分别对应于音调对的频率。在对谐波或非谐波音调对进行条件反射后，泛化梯度没有一致的差异。此外，还进行了实验，在交替试验中听到音调对中的两个音调，始终作为单音，随后进行对单音的泛化测试。在这个实验中有更多的泛化现象，这反映出条件反射和泛化测试刺激都是单音这一事实。然而，泛化梯度的形状与金鱼适应两个同时出现的音调时的形状相似，表明音调的同时性并没有使它们更难分离。随着两个成分之间的频率间隔变窄，分离往往会失败。
