Previous research has shown that the detectability of a local change in a visual image is essentially independent of the complexity of the image when the interstimulus interval (ISI) is very short, but is limited by a low-capacity memory system when the ISI exceeds 100 ms. In the study reported here, listeners made same/different judgments on pairs of successive "chords" (sums of pure tones with random frequencies). The change to be detected was always a frequency shift in one of the tones, and which tone would change was unpredictable. Performance worsened as the number of tones increased, but this effect was not larger for 2-s ISIs than for 0-ms ISIs. Similar results were obtained when a chord was followed by a single tone that had to be judged as higher or lower than the closest component of the chord. Overall, our data suggest that change detection is based on different mechanisms in audition and vision.

Phoneme-discrimination training improves experienced CI listeners' speech perception in noise. Additional research is needed to optimize auditory training for individual benefit.

In a test sound consisting of a burst of pink noise, an arbitrarily selected target frequency band can be "enhanced" by the previous presentation of a similar noise with a spectral notch in the target frequency region. As a result of the enhancement, the test sound evokes a pitch sensation corresponding to the pitch of the target band. Here, a pitch comparison task was used to assess enhancement. In the first experiment, a stronger enhancement effect was found when the test sound and its precursor had the same interaural time difference (ITD) than when they had opposite ITDs. Two subsequent experiments were concerned with the audibility of an instance of dichotic pitch in binaural test sounds preceded by precursors. They showed that it is possible to enhance a frequency region on the sole basis of ITD manipulations, using spectrally identical test sounds and precursors. However, the observed effects were small. A major goal of this study was to test the hypothesis that enhancement originates at least in part from neural adaptation processes taking place at a central level of the auditory system. The data failed to provide strong support for this hypothesis.