On the ability to discriminate Gaussian-noise tokens or random tone-burst complexes

This study investigated factors that influence a listeners' ability to discriminate Gaussian-noise stimuli in a same-different discrimination paradigm. The first experiment showed that discrimination ability increased with bandwidth for noise durations up to 100 ms. Duration had a nonmonotonic influence on performance, with a decrease in discriminability for stimuli longer than 40 ms. Further experiments investigated the cause for this performance decrease. They showed that discriminability could be improved when using frozen-noise tokens and by instructing listeners to focus on the stimulus endings. A final experiment, using a stimulus consisting of 5 ms Hanning-windowed tone-bursts randomly distributed over time, investigated whether stimulus duration and amount of information differently affect the processing capacity of the auditory system. Results showed that the number of degrees of freedom in the stimulus, not its duration, predominantly influenced the ability to discriminate. Overall, the results suggest that the discrimination performance for acoustic stimuli depends strongly on the amount of information per critical band and the capacity to process this information. This capacity seems to be limited in the temporal dimension, while extending the signal over more auditory filters does have a positive effect on performance.