Human Auditory Cortical Processing of Transitions Between ‘Order’ and ‘Disorder’

Auditory sensitivity to temporal deviations from perceptual isochrony: Comparison of the starting point and ending point of acoustic change1

“…If the time needed by the processing to perceive the acoustic change was shorter, it is likely that the temporal acuity would be better. Accordingly, the results of this study's experiments might be relevant to the findings by Chait et al. (2007).…”

“…The starting point of a transient part used in this study can be regarded as the change from “order” to “disorder” in the experiments by Chait et al. (2007).…”

“…The outputs of the model do not show consistency in the detected point around the frequency glides, and thus it is difficult to judge whether the detected point corresponds to the starting point of the glide or its ending point. This model simply considers the increment of the activity, neglecting the state of activity such as “order” or “disorder”, which has been identified as an important cue in detecting events accompanied by acoustical changes (Chait et al. 2007).…”

“…Several studies have shown that the detection of a new sound event is dependent on the characteristics of acoustic change. For instance, Chait, Poeppel, and Simon (2007) investigated early auditory cortical responses in humans using magnetoencephalography (MEG). They found that the processing for estimating acoustical regularity, that is, steady versus random, was sometimes dependent on the direction of change, either from “order” (e.g., a long sinusoidal tone whose frequency is fixed) to “disorder” (e.g., a sequence of short sinusoidal tones whose frequencies are varied) or vice versa.…”

“…In the context of the present study, the steady part in a continuous sound corresponds to “order”, and the transient part that connects consecutive steady parts to each other corresponds to “disorder”. From the suggestion of Chait et al. (2007), it is assumed that different kinds of processing are used between the conversion from a leading steady part to a transient part and that from the transient part to a following steady part.…”