Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2019 Oct 14;9:14734. doi: 10.1038/s41598-019-51352-0

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© The Author(s) 2019

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

PMC Copyright notice

Vocalization rates in preterm and full-term humans. Protophones are infant sounds produced mostly in exploration or play rather than in social interaction. The figure illustrates that protophones/minute generally exceeded cries/minute by a factor of >5 (error bars represent 95% confidence intervals, computed based on the raw data from each infant and independent of the modeled data from the GEE analyses) in randomly-selected five-minute infant-awake segments from all-day audio recordings. Even in the preterm infants, protophones were plentiful, more than two per minute even at two months before due date, suggesting deep natural selection for the tendency to produce endogenous vocalization in humans. GEE analysis indicated a significant increase in the protophone rate for preterms from - 2 to -1 month of age. The differences between protophone and cry rates were massively significant by t-tests. The groups of infants recorded longitudinally were 20 preterms at -2 and -1 month of age (that is, 32 and 36 weeks gestational age), 9 full term infants at 0 months (that is, during the first month after full term birth) and the same 9 plus 3 additional full-term infants through 12 months. Each infant at each age provided an all-day recording from which 24 five-minute segments were randomly selected for the human coding that yielded the estimated rates of vocalization.