Poster E54, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Speech encoding in quiet and background noise in 2 year olds
Sree Rajendran1, Cynthia Roesler1, Julie Morgan-Byrne1, Silvia Ortiz-Mantilla1, Gabriella Musacchia2,3, April Benasich1; 1Center for Molecular and Behavioral Neuroscience, Rutgers University - Newark, NJ, 2Department of Speech-Language Pathology and Audiology, University of the Pacific, 3Department of Otolaryngology Head and Neck Surgery, Stanford University Medical School
The maturation of proper speech perception ability depends on efficient neural encoding of rapid auditory changes in syllables, both in quiet and noisy background conditions. However, the impact of a noisy environment on speech processing at early developmental stages is unknown. The brain response to speech sounds has been reliably recorded and analyzed across the lifespan via the complex Auditory Brainstem Response (cABR) to the speech syllable /da/. The response comprises at least two major auditory mechanisms: the response to consonant onset (Waves V and A) and the frequency following response (FFR), which encodes the vowel periodicity. Collectively, these measures provide insight into the complexity of auditory processing involved in normal communication. We recorded monaural cABRs to /da/ with awake 24-month-olds in quiet (DaQ) and embedded in 60dB background noise (DaN). Waves V and A in DaN were delayed and attenuated, compared to DaQ. The deleterious effect of noise was also observed in the FFR at specific frequencies. This suggests that syllable perception at the brainstem level is vulnerable to disruption as a result of background noise. Strong and significant correlations were observed within onset measures (i.e. between waves V and A) and within FFR measures, but not between onset and FFR measures. This finding supports the idea that infants have developed independent mechanisms for encoding transient and sustained features of speech by 24 months-of-age. Our findings are the first reported in 24-month-olds, who are experiencing a burst in language development.
Topic Area: LANGUAGE: Development & aging