The temporal dynamics of auditory memory for static and dynamic sounds

A challenge to research on auditory and speech perception has been a lack of correlation between measures of each ability, despite their shared acoustical basis. The hypothesis presented here is that stimuli in the auditory domain stimuli generally have a static quality whereas stimuli in the speech domain generally have a dynamic quality, but attempts to correlate the two assume that static and dynamic stimuli are processed similarly by auditory short-term memory (ASTM). This thesis utilizes a change-detection task, which is popular for investigating the function of visual short-term memory, to more closely examine the function of ASTM for the purpose of evaluating the plausibility of this hypothesis. Across three experiments the temporal dynamics of ASTM are explored by manipulating the interstimulus interval (ISI), the stimulus duration, and the type of feature change in a change-detection task. This final manipulation (Experiment 3) also involves change-detection in a sequence of stimuli rather than just pairs of stimuli (as in Experiments 1 & 2). Individual differences in ASTM function are also evaluated in order to ensure that any differences found are present for all listeners and to further understand the function of ASTM. It is found that ASTM for static stimuli is consistently better than dynamic stimuli, even for listeners with high ASTM performance. Longer ISIs lead to poorer performance only for dynamic stimuli and only for participants who show poor ASTM function at long ISIs. Longer durations lead to better performance for all stimuli to a point, but performance for dynamic stimuli plateaus, and even decreases, at the longest durations, while the static stimuli continue to show gains. This result generally holds for all listeners. Lastly, changes in temporal order and changes to stimuli at the end of the sequence are detected more often than changes in frequency and large changes are detected more often than small changes. These first two effects hold for all stimuli while the second effect is more true of static stimuli. These results are discussed within the context of ASTM and the impact of each manipulation on the encoding, maintenance, and comparison processes is considered.