The ASHA Leader - September 21, 2010 - (Page 5)

Biological Markers of Reading and Speech-in-Noise Perception in the Auditory System by Nina Kraus and Jane Hornickel anguage-based learning impairments occur in 5%–10% of school-aged children (Shapiro, Church, & Lewis, 2007). Children with language-based learning impairments are more greatly affected by background noise than their typically developing peers (Bradlow et al., 2003; Ziegler et al., 2009) and may be at a particular disadvantage in noisy classrooms, which in one survey were as loud as a busy traffic intersection (Shield & Dockrell, 2003). Researchers at the Auditory Neuroscience Lab at Northwestern University have found that children with language-based learning impairments can have atypical neural representations of speech in their auditory systems. Moreover, background noise compromises auditory encoding of sound to a greater extent in these children compared to their typically developing peers. These neural markers, described below, are associated with language and listening skills such as speechin-noise perception and reading ability and reflect a biological basis for these abilities. L Both of these studies revealed that poor readers had impaired brainstem encoding of speech relative to good readers, and that these impairments were correlated with the perception of speech in noise. Because the nervous system communicates through electricity, the coordinated responses of neurons in the auditory brainstem to sounds can be recorded; these responses are called the auditory brainstem response (ABR). For decades ABR has been used as a clinical measure of auditory function, and it has been used more recently as an objective measure of auditory processing of complex sounds, such as speech and music (for a review, see Skoe & Kraus, 2010). Brainstem activity also is experience-dependent and is shaped by lifelong experience with music or language as well as by short-term training (Parbery-Clark et al., 2009; Krishnan et al., 2005; Russo et al., 2005). The brainstem response can reflect the acoustics of the sound played to the ear, including the pitch, timing, and harmonics of the sound with remarkable fidelity. Children with language-based learning impairments have poorer brainstem encoding of the timing and harmonics of sound, which are important for the perception of certain consonants, but not the pitch of the sound (Banai et al., 2009). Stop consonants are particularly difficult to understand in the presence of background noise and they are particularly difficult to understand—even in quiet—for children who have language-based learning and listening disorders (Miller & Nicely, 1955; Tallal & Piercy, 1974, 1975). Study Results In our lab, two recent studies have linked the biological encoding of stop consonants with listening to speech in noise and reading skills. First, poor readers were found to have poorer brainstem representation of the neural timing necessary to distinguish stop See Biological Markers page 6 Audiology in Brief New Meningitis Test Could Save Lives Researchers at Queen’s University Belfast and the Belfast Health and Social Care Trust in Northern Ireland, UK, have developed a groundbreaking, life-saving test for meningitis that can produce results within an hour. Current tests for meningococcal infections produce results in 24 and 48 hours. Early detection also can potentially improve outcomes for meningitis patients who often are left with life-altering conditions such as deafness and cerebral palsy. “The new test, called loop mediated isothermal amplification (LAMP), uses a molecular method to detect genes that are common to all strains on the meningococcus,” said researcher Mike Shields. “The real advantage of the new LAMP test is that it has the potential to be a simple bedside test that is rapid, cheap, easy to use, and doesn’t require laboratory trained staff.” Visit www.qub. ac.uk/home/theUniversity/ Generalservices/news/ Pressreleases. range that is challenging the conventional wisdom that what we can’t hear won’t hurt us. Infrasound—defined as any sound lower than 20 Hz, the lowest pitch that most people can hear—is all around us. Although barely perceptible, it can create problems such as headaches, irritability, or difficulty concentrating in people who live close to wind turbines. Researchers at the University of St. Louis hypothesize that the outer hair cells (OHC) in the cochlea are highly sensitive to infrasound, but when they encounter it, their proteins don’t contract and expand like they do for sound frequencies in the acoustic range. Instead, the proteins work to prevent movement of the inner hair cells so that sound is not detected. Although the brain may not hear the sound, the OHC responses to it could influence the function of the inner ear and cause unfamiliar sensations. It’s unclear why some people are more sensitive to infrasound than others. Researchers postulate that it may be possible to change the design of wind turbines to minimize infrasound by locating the rotor further away from the pole. For more information, visit www.nidcd.nih.gov/news/ releases/10/07_28_10.htm. loss. In a study that evaluated 51 children with DRTA, 11 patients—or 40.7%—had bilateral sensorineural hearing loss. The researchers also found that a significant percentage of the children with DRTA had sensorineural hearing loss and a mutation in the ATP6VB1 gene. These children showed no recovery of hearing with alkali treatment. The researchers recommend investigating the possibility of hearing loss in all children with DRTA. The full-text article is available in the July issue of the Iranian Journal of Kidney Diseases at www. ijkd.org/index.php/ijkd. If you’d like to submit an article idea or provide feedback on this audiology page, send an e-mail to leader@asha.org. Wind Turbine Design and Noise Wind turbines are becoming increasingly popular as a “green” energy source, but a design change may be needed to minimize the effects of their lowfrequency sound. As their large rotors move, wind turbines generate a noise in the infrasound Kidney Disease Linked to Hearing Loss Children with distal renal renal tubular acidosis (DRTA), a disorder that results in an accumulation of acid in the body, may have hearing September 21, 2010 5 http://www.qub.ac.uk/home/TheUniversity/GeneralServices/News/PressReleases http://www.qub.ac.uk/home/TheUniversity/GeneralServices/News/PressReleases http://www.nidcd.nih.gov/news/releases/10/07_28_10.htm http://www.nidcd.nih.gov/news/releases/10/07_28_10.htm http://www.ijkd.org/index.php/ijkd http://www.ijkd.org/index.php/ijkd

Table of Contents for the Digital Edition of The ASHA Leader - September 21, 2010

The ASHA Leader - September 21, 2010
Contents
Teens at Risk: "We're on the Edge of an Epidemic"
Bottom Line
Audiology
New Fluency, Cognition Diagnosis Codes
Schools 2010: Learning and Leadership in Las Vegas
RTI Progress-Monitoring Tools
Classroom Acoustics: What Possibly Could Be New?
Schools Practice: New Research and Online Resources
From the President
Schools Survey Caseload Data
Internet
Identification and Treatment of Landau-Kleffner Syndrome
Buyers Guide
Classifieds
First Person on the Last Page

The ASHA Leader - September 21, 2010