Funded Grants

A naturalistic examination of the listening environment and its role on development

This project examines the relation between environmental noise and the development of early language and cognitive skills. Children have greater difficulty than adults processing speech in noise. Infants are especially vulnerable to noise, and need higher signal-to-noise ratios to understand speech. Noise exposure affects critical processes in language acquisition (e.g., learning and recognizing words) and cognitive performance (e.g., sustained attention), and is linked to negative health and developmental outcomes. Furthermore, it is significantly harder for bilinguals than monolinguals to process speech in noise; this group difference is present with different noise types and age groups. However, the data available has come primarily from artificial laboratory measures, and from children raised in mid-socioeconomic status (SES) families who have the means to travel to labs. Little is known about the effect of noise pollution on cognitive and linguistic development in children from at-risk communities. The reality is that bilingual homes in America are disproportionally low SES, with Latino dual-language learners making up the largest group. Children in these families are at a higher long-term risk for academic failure. Critically, poverty is also linked to more noise exposure from traffic, airports, and from sources in the home. Thus, it is important to understand (i) how environmental noise affects cognitive and linguistic performance in a wider range of infants (including those raised in bilingual environments and in low-SES communities), and (ii) what mechanisms might help explain the relation between noise exposure and early cognitive and linguistic abilities. There is evidence suggesting that exposure to noise disrupts the emergence of sound representations in the brain, which are needed to process auditory input (especially spoken language). With this in mind, this project combines neural (Cortical Auditory Evoked Potentials measured with a portable system), behavioral (portable eye-tracking), and naturalistic measures of the home listening environment (wearable recorders that collect ecologically-valid measures of sound sources). We will document the characteristic of the listening environment in which infants are being raised, and examine how this factor influences auditory cortex development, and the acquisition of early cognitive and linguistic skills. Specifically, our data will allow us to determine whether infants who have greater exposure to noise in their home show poorer auditory cortex function and delayed language and cognitive performance and whether negative effects of noise are different in bilinguals compared to monolinguals. These goals will be achieved employing a longitudinal design in which measures are collected in the home across timepoints when children are between 9 and 18 months. This is a timeframe in which there are significant changes in infants’ cognitive and linguistic skills that are critical for future development. The portability of the experimental setup will enable testing of infants from mixed socioeconomic backgrounds, allowing us to explore this factor as a covariate. The signal-to-noise ratio (e.g., limiting the amount of time that the TV is on in the background, improving classroom building codes) may be malleable. Thus, understanding the role of noise on language and cognitive development will be a key outcome.