Everyday music in infancy

Abstract

Infants enculturate to their soundscape over the first year of life, yet theories of how they do so rarely make contact with details about the sounds available in everyday life. Here, we report on properties of a ubiquitous early ecology in which foundational skills get built: music. We captured daylong recordings from 35 infants ages 6-12 months at home and fully double-coded 467 h of everyday sounds for music and its features, tunes, and voices. Analyses of this first-of-its-kind corpus revealed two distributional properties of infants' everyday musical ecology. First, infants encountered vocal music in over half, and instrumental in over three-quarters, of everyday music. Live sources generated one-third, and recorded sources three-quarters, of everyday music. Second, infants did not encounter each individual tune and voice in their day equally often. Instead, the most available identity cumulated to many more seconds of the day than would be expected under a uniform distribution. These properties of everyday music in human infancy are different from what is discoverable in environments highly constrained by context (e.g., laboratories) and time (e.g., minutes rather than hours). Together with recent insights about the everyday motor, language, and visual ecologies of infancy, these findings reinforce an emerging priority to build theories of development that address the opportunities and challenges of real input encountered by real learners.

Keywords: LENA; enculturation; everyday ecologies; infancy; input; music.

FIGURE 1

Example of high inter‐rater reliability for identifying music and the distributional structure of its voices in one daylong recording. (A) Music bouts: Coder 1 and Coder 2 identified music bouts (purple) throughout the recording. (B) Voices: Coder 1 and Coder 2 identified the specific voices in this recording's vocal bouts (voice identities printed here are fictional, in order to maintain family privacy). Blue tiles show the intersection of Coder 1′s and Coder 2′s identity for each bout; darker tiles indicate a larger number of bouts. This illustration of contingency shows reliable distributional structure (e.g., Coder 1′s ‘Friend’ and Coder 2′s ‘Neighbor’ uniquely identified this voice) with one minor deviation from perfect agreement (e.g., Coder 1 distinguished “FolkSinger” from “CountrySinger” while Coder 2 identified both voices as “LullabySinger”).

FIGURE 2

The feature space of everyday music in infancy. Each cell shows the proportion of bouts containing music with the features of its row by column intersection. Lighter colors indicate denser parts of the feature space.

FIGURE 3

One illustrative distribution of tunes showing an observed daily distribution (top row, black) that is not consistent with a uniform identity space (bottom row, blue). The blue plus sign shows the proportion for one tune identity expected from uniformly distributed identities and the thick orange line shows the proportion of the most available observed tune identity (“Baby tune”). See text for super availability computation.

FIGURE 4

Non‐uniformly available tune and voice identities in individual daylong recordings of everyday music in infancy. Each row is one recording, segmented into unique identities organized from most‐to‐least available (left‐to‐right). The observed proportion of each recording's most available identity (thick white vertical line) exceeded the per‐identity proportion expected from uniformly distributed identities (small white +) in daily distributions of (A) tunes and (B) voices. Recordings in each panel are sorted according to the uniform per‐identity proportion.

FIGURE 5

Non‐uniformly available tune and voice identities in a corpus of everyday music in infancy. The duration of observed identities in this corpus (dark) cumulated to more extreme shorter and longer daily durations than would be expected if uniformly distributed (light) across the daily seconds of (A) tunes and (B) voices. For visualization, histogram bin‐widths were determined with respect to each distribution using Scott's rule (Scott, 1979): h_n = 3.49σn ^‐1/3.

FIGURE 6

Pre‐enculturation sensory history: an estimated year of everyday music. Lines show linear extrapolation of the minimum (459 s per day; dark green), median (3,311 s per day; green), and maximum (15,626 s per day; light green) daily musical seconds observed in the present corpus. Waking hours were estimated following Galland et al. (2012).