The origin of language and relative roles of voice and gesture in early communication development

Origins of vocal-entangled gesture

“…This increase in rattling co-occurred with increases in rhythmic manual (but not leg) actions. Importantly, a sharp increase in rhythmical actions in the exact same period wherein infants rapidly increase their canonical babbling has now been reported in a whole host of studies (Burkhardt-Reed et al, 2021;Cobo-Lewis et al, 1996;Eilers et al, 1993;Locke et al, 1995;Thelen, 1979). Further, when babbling is delayed, rhythmic manual behaviors and postural stability are also reduced .…”

“…Recently it was shown that vocalizations are about 35 times more abundant in infant communication than the use of gestures, especially in early developmental phases of about 4 months. However, in later phases (7 and 11 months), vocalizations are reduced and gestures increased, but still ending with about 2.5 times more vocalizations than gestures (Burkhardt-Reed et al, 2021). Though not central to their findings, the authors also found that "non- While gestures may not be more primary, there is an interesting well-replicated phenomenon that directs us to the possibility that gestures guide speech-like vocal development.…”

Longitudinal changes in infants' rhythmic arm movements during rattle-shaking play with mothers

“…Third, rhythmic arm movements are postulated to be the precursor of vocal-entangled gestures that accompany day-to-day adult communication (Pouw and Fuchs, 2022). As was shown in previous studies (Thelen, 1979;Locke et al, 1995;Ejiri, 1998;Ejiri and Masataka, 2001;Iverson and Fagan, 2004;Iverson and Wozniak, 2007;Burkhardt-Reed et al, 2021), rhythmic manual movements often co-occur with infants' vocalizations and this co-occurrence is observed at much earlier developmental stages than other types of gestures-such as pointing (emerging around 12 months of age; Colonnesi et al, 2010;Murillo et al, 2021) or iconic gestures (emerging around 26 months of age, Ozcaliskan and Goldin-Meadow, 2011). Thus, it seems that rhythmic arm movements that accompany vocal learning may serve as a precursor to the gesture-speech system (Iverson and Fagan, 2004;Pouw and Fuchs, 2022).…”

A Preliminary Longitudinal Study on Infant-Directed Speech (IDS) Components in the First Year of Life

“…The talk of mothers (see Figure 2 ), both in the different recording sessions (intra-mom) and between the recordings (inter-mom), had similar acoustic parameters. The fundamental frequency or first harmonic, which perceptually corresponds to the height (or tone) of the sound produced, of a conversational speech is on average between 70 and 150 Hz for a male voice, between 150 and 250 Hz for a female voice, and between 250 and 350 Hz for a child’s voice [ 36 ]. The values found for mothers in this study were all between 150 and 450 Hz (M = 302; D.S.…”