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Baby’s First Words: Language Acquisition in a Noisy Environment

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During the first formative years of a child’s life, they are bombarded with all kinds of information. Before their exciting first words, they must extract the relevant sounds from a noisy environment filled with bickering siblings, loud TVs and radios, and grownups talking. Babies have an amazing ability to determine the important sounds of their native language during the critical language learning period. In a fascinating Ted Talk, MIT researcher Deb Roy tracked his son’s learning of the word “water” from the babble “gaga”, to the correct pronunciation, over the course of half a year using audio and video feeds all around the house. His son’s brain was hard at work piecing together the connection between the visual and audio inputs. A lot of research has been done on the impact of noise on school-age children, but more research is showing that noise levels can inhibit a young child’s ability to learn words.

Children spend a large portion of their time in noisy environments (e.g. daycares). External factors like traffic noise vary depending on geographic area, with urban environments often suffering from higher background noise levels. The quality of building construction and even family size also play a large role in the home soundscape. Multiple people talking simultaneously, or a TV constantly on in the background can further degrade the listening environment. Some noises are more intrusive than others: loud, intermittent sounds like the honk of a car horn may be more distracting than steady-state noises like the hum of an HVAC system. In particular, when background noise is also speech, the target signal can be very difficult for infants to identify.

It is important to recognize that infants’ brains do not process speech in noise in the same way that adults do. Adults have the advantage of a larger knowledge base, and can rely on similar experiences and context clues to enhance understanding, so they can fill in gaps when information is unintelligible. The cocktail party effect (covered in another Acentech blog) doesn’t really exist for these young listeners. Infants and young children need a higher signal-to-noise ratio than adults to perceive speech successfully. A study out of the University of Wisconsin-Madison found how children of different ages were able to separate speech streams when presented with multiple speakers in the background. A 13-month-old can recognize their name when it is presented at a level 5 dB higher than the background speech, but 5- and 9-month-old infants need their name to be 10 dB higher in intensity than the background.

While it is impossible to create a noise-free environment to raise children, the study found that children were able to increase their word-learning abilities when a new word was first presented without background noise before matching the new word to an object. This finding is supported by another study that suggests the increased difficulty of perception drains cognitive resources away from the establishment of a robust memory trace, which can be alleviated by setting aside quiet time to teach a child.

Although background noise can impair learning, in certain situations noise can enhance learning, in particular, steady-state maskers at low volumes. These are often implemented in an office environment to cover up intermittent noise, and explain why some people like to sleep with noise generators (ex. fans). Other studies indicate the importance of the introduction to music at a young age.

A lot of attention is paid to classroom acoustics to ensure a healthy learning environment, but the home environment is proving equally important. Difficulties in early language learning can lead to future academic challenges, where a large portion of the learning relies on instructor oral delivery. A study of income-controlled housing built over a highway in New York City found that the school-aged children in the lower, noisier floors exhibited poorer auditory discrimination skills, which were correlated with their reading abilities. Developers, designers, and government officials all need to focus on this emerging issue to limit the impacts noise can have on child development.

These findings stress the importance of sound isolation design for residential buildings and daycare centers in noisy urban environments. Noise levels can be reduced through a variety of means, including covering hard surfaces with softer (sound-absorbing) materials; glazing or replacing windows; and maintaining or replacing HVAC systems for maximum efficiency. Turning off the TV and being cognizant of the other noise you generate within the home can help create an environment that encourages learning at a young age. Your child (and your neighbors) will thank you!