Audiology In Brief Short-term hearing loss at any age—such as conductive hearing loss from otitis media with effusion—can produce long-lasting deficits in auditory acuity (“lazy ear”), much like the analogous ophthalmologic condition (“lazy eye”) in which the brain has trouble processing signals from a functional eye. A study in the March 11 ... News in Brief
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News in Brief  |   April 01, 2010
Audiology In Brief
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Hearing Disorders / News in Brief
News in Brief   |   April 01, 2010
Audiology In Brief
The ASHA Leader, April 2010, Vol. 15, 5. doi:10.1044/leader.NIB.15052010.5
The ASHA Leader, April 2010, Vol. 15, 5. doi:10.1044/leader.NIB.15052010.5
Ear Infections Can Cause “Lazy Ear”
Short-term hearing loss at any age—such as conductive hearing loss from otitis media with effusion—can produce long-lasting deficits in auditory acuity (“lazy ear”), much like the analogous ophthalmologic condition (“lazy eye”) in which the brain has trouble processing signals from a functional eye. A study in the March 11 Neuron shows that the brain’s auditory cortex remains flexible enough to rewire itself partially even into adulthood. The study found that monaural deprivation distorted tonotopic maps of sounds of various frequencies in the auditory cortex, weakened the representation of sounds from the deprived ear, and strengthened the representation of sound in the open ear. The binaural integration of interaural-level differences also was disrupted. The animal experiment showed that the brain has a number of critical windows for rewiring itself, and the effects of monaural auditory deprivation produced different changes in the rats’ brains, depending on the age when hearing was impaired.
Hearing Aids Associated With Old Age
A survey conducted by the Phonak Hearing the World initiative has found that despite significant advances in hearing technology, hearing aids were associated with old age more than any other accessory surveyed, including glasses, a wheelchair, crutches, and canes for individuals who are blind.
According to the survey, which polled 4,405 people ages 14–65 in the United States, France, Germany, Switzerland, United Kingdom, and Italy, one of the top three reasons for not wearing a hearing aid was the desire not to admit publicly to the presence of hearing loss.
The survey, however, also showed that 93% of respondents would wear a hearing aid if it was necessary.
Unilateral Hearing Loss and the Brain
The brains of children with unilateral sensorineural hearing loss (USNHL) show significant differences in how they process sound. In addition, sound is processed differently depending on which ear has hearing loss.
Using functional magnetic resonance imaging (fMRI), researchers compared neuroanatomic activation patterns in children with USNHL to those patterns in children with normal hearing while the subjects listened to narrowband noise and speech-in-noise tasks. In the narrowband noise task, children with USNHL exhibited less activation of auditory areas in general and specifically less activation in auditory association areas and attention networks compared to children with normal hearing.
In the speech-in-noise task, children with USNHL exhibited activation in secondary auditory processing areas only in the left hemisphere; the children with normal hearing exhibited activation in these same areas bilaterally.
Different patterns of neural activation were associated with hearing loss in the right or left ear. Children with right-sided hearing loss exhibited less activation in attention areas than children with normal hearing and children with left-sided hearing loss. Only children with left-sided USNHL exhibited activation bilaterally in visual association areas.
These differences may explain some of the functional auditory problems experienced by children with USNHL. Visit the January 2010 issue of Archives of Otolaryngology—Head and Neck Surgery.
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April 2010
Volume 15, Issue 5