February 1, 2013 Departments

From the Journals: February 2013

More Education Improves Failed Hearing Screening Follow-Up

Underserved communities may need extra support to navigate the steps that follow failed newborn hearing screenings, according to a study in the December 2012 issue of the American Journal of Audiology. With delayed identification of permanent childhood hearing loss a major public health concern, the authors suggest continuing public awareness campaigns and education of providers and families about hearing loss.

Study researchers sought to document the epidemiological characteristics of a group of children who are hard of hearing, identify individual predictor variables for timely follow-up after a failed newborn hearing screening, and identify barriers to follow-up that families encounter.

The authors used an accelerated longitudinal design to investigate outcomes for children who are hard of hearing in a large, multicenter study. The AJA-published study involved a subgroup of 193 children with hearing loss who did not pass the newborn hearing screening. Researchers used available records to document the ages of children when they were confirmed to have hearing loss, received hearing aid fittings and entered into early intervention. They used linear regression models to investigate relationships among individual predictor variables and age at each follow-up benchmark.

Of several predictor variables, only higher levels of maternal education were significantly associated with earlier confirmation of hearing loss and fitting of hearing aids. The severity of the hearing loss was not. No variables were significantly associated with age of entry into early intervention. A majority of children met each recommended benchmark, but only one-third met all the benchmarks within the recommended time frame.

Preschoolers Understand Human Speech Better Than Synthesized Speech

Although preschool children understand synthesized speech in typical listening environments, and can improve their listening accuracy with repeated exposures, their understanding doesn't reach the same level of accuracy as with human-recorded speech, according to a study in the November 2012 American Journal of Speech-Language Pathology.

The study examined the effect of repeated exposure to novel and repeated spoken words in typical environments on the intelligibility of two synthesized voices and human-recorded speech. Eighteen preschoolers listened to and repeated single words presented in human-recorded speech and in DECtalk Paul and AT&T Voice Michael—two varieties of speech-synthesizing software—during five experimental sessions in the presence of noise typical of classroom or home settings.

There was a significant main effect for voice. Participants were more accurate in identifying words in the human-recorded speech and AT&T Voice than in the DECtalk speech output condition. When averaged across speech output conditions, children increased their accuracy as they participated in additional sessions. There was a statistically significant interaction between session and voice. DECtalk had a slightly larger effect of session than did AT&T Voice and human-recorded speech.

Rare Words Easier to Learn Than Common Ones

Preschoolers with typical development and those with specific language impairment show an advantage when learning rare words as opposed to common ones—an advantage that isn't restricted to the first few exposures to words, but continues over time, according to a study in the October 2012 issue of the Journal of Speech, Language, and Hearing Research.

In the study, the authors tried to replicate previous findings that preschoolers have a greater advantage when learning rare (low phonotactic probability) words than when learning common (high phonotactic probability) ones, whether this advantage would be apparent at different "stages" of word learning, and whether findings would differ for preschoolers with specific language impairment and typical development.

Participants included 114 children: 40 with specific language impairment, 39 with typical development matched for age and gender and 35 with typical development matched for expressive vocabulary and gender. Researchers assessed comprehension and production during word learning and at post-test for words that varied in phonotactic probability and object familiarity.

Across groups, comprehension performance increased significantly from days one to two and from days two to three, but there was no significant effect of word or object type. Production performance increased significantly from days one to two, from days two to three, and from days three to four for all groups, and there was a clear advantage when learning rare words and unfamiliar objects, but not at post-test. The study illustrates how the interaction of phonological characteristics in nascent and extant words can affect word learning.

Age and Treatment Intensity Prove Key in Autism

A child's age and intensity of treatment—but not the type of treatment or who delivered it—were associated with better behavioral outcomes for toddlers at risk for autism spectrum disorders, according to a study in the October 2012 issue of the Journal of the American Academy of Child and Adolescent Psychiatry.

Researchers studied 98 families of children, ages 14 to 24 months, who were at risk for autism spectrum disorders. They sought to determine the efficacy of a 12-week, low-intensity, parent-delivered intervention. In this three-site, randomized controlled trial, some children received usual community treatment, and others participated in the Early Start Denver Model.

In this model, parents receive instruction on using a child-centered responsive interaction style that embeds many teaching opportunities into play. Assessments were completed at baseline and 12 weeks later, immediately after the end of parent coaching sessions.

Group assignment had no effect on parent-child interaction or on any child outcomes. Both groups of parents improved interaction skills, and both groups of children demonstrated progress. Children in the community group received significantly more intervention hours than those in the parent-implemented intervention group.

Study evidence—that both younger age and more intervention hours positively affect developmental rates—holds implications for clinical practice, service delivery and public policy.

Air Quality May Affect Infants' Brains

Research demonstrates that polluted air—whether regional pollution or from local traffic sources—is associated with autism, according to a study published online in November 2012 by Archives of General Psychiatry.

The study, conducted by University of Southern California and Children's Hospital Los Angeles scientists, included 279 children with autism and 245 children with typical development. The results suggest that exposure to traffic-related air pollution during pregnancy and the first year of life is associated with a more than two-fold risk of autism. In addition, exposure to regional pollution consisting of nitrogen dioxide and small particles is also associated with autism even if the mother did not live near a busy road.

The research is the first to look at the amount of exposure to near-roadway traffic pollution and to combine that with measures of regional air quality. The study builds on previous research that examined how close participants lived to a freeway. The researchers are now working on a study of how genes related to autism may be affected by environmental exposures to determine if certain factors make people genetically more vulnerable to particular pollutants.

Virus Associated With Developmental Delays and Deafness

Primitive human stem cells are resistant to human cytomegalovirus, one of the leading prenatal causes of intellectual disability, deafness and deformities worldwide, according to a study published online in November 2012 in PLOS ONE.

Researchers from the University of Pittsburgh School of Medicine found that as stem cells and other primitive cells mature into neurons, they become more susceptible to CMV, a finding that could allow them to find effective treatments for the virus and to prevent its potentially devastating consequences. The study authors derived live human-induced pluripotent stem cells by reprogramming cells called fibroblasts from human skin biopsies. They induced the stem cells to mature through several stages into neurons—the primary cells in the brain—and evaluated the patterns of damage caused by CMV on all these cells.

Findings indicate that human-induced pluripotent stem cells do not permit a full viral replication cycle, suggesting for the first time that these cells can resist CMV infection. Further, CMV infection distorts stem cells' differentiation into neurons, a mechanism by which infected babies may develop impairments of brain maturation and intellectual ability.

According to the U.S. Centers for Disease Control and Prevention, one of every 150 children is born with CMV infection, and one in five of them develops permanent problems, such as intellectual disability, vision and hearing loss, and seizures. Researchers are collaborating with the Drug Discovery Institute to further understand the cellular system and determine which agents are most effective against HCMV and similar viruses, and which treatments would be safe for human use.

Accuracy of Lexical Stress Critical to Reading Success

Morphophonology—accurately produced lexical stress in derived words—involving suprasegmental factors (for example, tone, stress, prosody) may be an area of similarity among different languages or dialects and has a consistent relationship to word reading. Stress accuracy was consistently related to reading measures, even when phonological and morphological awareness were not, according to a study in the October 2012 issue of Language, Speech,and Hearing Services in Schools.

The authors examined the influence of demographic variables on nonmainstream American English use; the differences between nonmainstream American English speakers and mainstream American English speakers on measures of metalinguistics, single-word reading and a new measure of morphophonology; and the differences between the two groups in the relationships among the measures.

Participants were 42 typically developing third-graders from Memphis, Tenn., half who spoke mainstream American English and half who spoke nonmainstream American English. The children received a battery of tests measuring phonological and morphological awareness, morphophonology, decoding, and word identification.

Controlling for socioeconomic status, results indicated that measures of phonological awareness, decoding and word identification were higher for mainstream American English than for nonmainstream American English speakers. There was no difference in stress accuracy between the dialect groups.

Only for the nonmainstream American English group was phonological and morphological awareness significantly related to decoding and word identification. Stress accuracy was correlated with word reading for the nonmainstream American English speakers and with all measures for the mainstream American English speakers.

Lyrical Improvisation Reallocates Brain Function

Vocal improvisation or "freestyling"—spontaneously improvising lyrics in real time—is associated with a unique functional reallocation of brain activity in the prefrontal cortex, according to a study in the Nov. 15 issue of Scientific Reports.

Researchers in the voice, speech and language branch of the National Institute on Deafness and Other Communication Disorders at the National Institutes of Health used functional magnetic resonance imaging to study the brain activity of rappers as they improvised lyrics. They scanned the brains of 12 freestyle rap artists—each of whom had at least five years of rapping experience—while the rappers performed two tasks using an identical eight-bar musical track.

For the first task, rappers improvised rhyming lyrics and rhythmic patterns guided only by the beat. In the second task, they performed a well-rehearsed set of lyrics. During freestyle rapping, the researchers observed increases in brain activity in the region responsible for motivation of thought and action, but decreased activity in regions that normally play a supervisory or monitoring role. Like an experienced parent who knows when to lay down the law and when to look the other way, these shifts in brain function may facilitate the free expression of thoughts and words without the usual neural constraints.

Further studies of this network in other art forms that involve the innovative use of language—such as poetry and storytelling—could offer more insights into the initial, improvisatory phase of the creative process.


  

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