Too noisy for toddlers

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Science Translational Medicine  05 Aug 2015:
Vol. 7, Issue 299, pp. 299ec132
DOI: 10.1126/scitranslmed.aac9318

Given the pervasive nature of handheld devices such as tablets and cell phones, exposure to a cacophony of conversations, music, and random beeping, pinging, and ringing, is an integral part of our daily experience. Although some take pride in their ability to engage in cognitive multitasking, a new study by Niemitalo-Haapola et al. suggests that such activities might be for adults only.

The authors evaluated the effects of background noise on how the brain processes speech sounds in typically developing toddlers. Spurred on by previous findings in adults and school-age children showing that background noise affects how the brain encodes and distinguishes speech, the investigators tested 18 monolingual children with healthy ears who were between 22 and 26 months of age. The children were presented with a series of standard syllables interspersed with an unexpected, or deviant, syllable in the presence or absence of background noise. To understand how the brain processes speech, researchers placed a host of electrodes on the scalp of each toddler and obtained electroencephalograms (EEGs) from the subjects under a variety of conditions. The EEG electrodes detected the combined electrical activity of brain cells, called event-related potentials, in response to linguistic sequences. The findings revealed multiple effects of background noise on event-related potentials, indicating that the cacophony affects early stages of sound-encoding—the process by which the human brain receives sound as a sensation and maps it to perception—and hinders the brain’s ability to discriminate among sounds that are critical for accurate speech perception.

These observations suggest that noise adversely affects speech processing in toddlers. Given that toddlers may be exposed to noisy conditions for long periods in daycare settings, special attention should be given to ensuring that acoustic conditions are managed, especially for children with linguistic problems who might be more adversely affected. The current study measured only EEG signals that resulted right after presentation of the speech+noise regimen. Considering how crucial communication is in most career settings, it will be important to investigate whether stunting of linguistic development by a noisy early childhood has long-term detrimental effects.

E. Niemitalo-Haapola et al., Background noise degrades central auditory processing in toddlers. Ear Hear. 10.1097/AUD.0000000000000192 (2015). [Abstract]

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