Figure 1.

The circles in the top panel show the onsets of automatically-identified vocalizations in a 9-month-old infant’s day-long audio recording. The horizontal position of each circle represents time, with left being earlier in the day and right being later in the day. It is apparent that the infant vocalized in clusters over the day, with some of the clusters being denser and/or lasting longer than others. The area with gray background is an hour-long period and forms the basis of the middle panel. The middle panel thus presents a zoomed-in version of the top panel. It can be seen that within that hour, the infant vocalized in clusters, with the pattern of clustering appearing similar to the clustering at the day-level even though the timescale is much smaller. The area with gray background is a 5-minute-long period and forms the basis of the bottom panel. It is apparent that even within the 5-minute period, the infant vocalized in clusters. Again, the nature of the clustering shows similarity in its patterning to the clustering at hour-long and day-long scales. This figure thus highlights that there is fractality, i.e., self-similarity when zooming in or zooming out, in the how infant vocalizations pattern into clusters over time.