Right to Quiet Society Noiseletter
Winter 2012, page 5

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Dyslexics struggle with blocking background noise

By Mimi Nguyen Ly, Epoch Times Staff

Dyslexia is a language-based learning disability with symptoms including reading, writing, and spelling problems. Dyslexia may be partly due to difficulty in excluding external noise, according to a new U.S. study. Symptoms of this language-based learning disability include reading, writing, and spelling problems. It affects 5 to 17.5 percent of the population, but the causes are not yet fully understood. Researchers from The Ohio State University and University of Southern California looked at how 37 undergraduate students performed letter detection tasks involving variations in letter sizes and background noise.

The students were divided into two groups based on their reading abilities - 21 met the criteria for the average to above average readers group, while 16 qualified for the

poor readers group. The team found that the poor readers performed significantly worse at the tasks when there was high background noise, irrespective of letter size. However, when there was no background noise, both groups per-formed similarly. “These findings support a relatively new theory, namely that dyslexic individuals do not completely filter out irrelevant information when attending to letters and sounds,” says study lead-author Rachel Beattie in a press release.

“This external noise-exclusion deficit could lead to the creation of inaccurate representations of words and phonemes and ultimately, to the characteristic reading and phonological awareness impairments observed in dyslexia.”

The study was published in the online journal PLoS ONE on Nov. 23, 2011.


Dolphin echo-locating abilities may diminish due to man-made noise

Epoch Times Staff, October 31, 2011

Marine mammals may be significantly affected by under-water noise such as ship sonar and oil well operations, according to new research from the United States. Dolphins and whales use sound echoes to navigate and communicate via a process called echolocation. A study by the U.S. Navy and the National Marine Mammal Foundation shows that anthropogenic noise in general and particular noise frequencies may affect dolphins’ ability to echolocate.

Scientists at the Navy Marine Mammal Program (NMMP) facility detected a male bottlenose dolphin’s clicks with a hydrophone, and then created a computerized echo that was played back to him with a delay. The researchers generated echoes to simulate an object, both stationary and rotating, about 10–56 feet (3–17 meters) away from the dolphin by altering the delay.

The dolphin was taught to make a buzzing sound upon detecting a change in the echo from that of a stationary to a rotating object.

During the experiment, the team played seven different man-made noises at various frequencies and durations along with the echo to see how each one affected the dolphin’s ability to hear when the echo changed. “Preliminary results show that intermittent noise at frequencies outside of the echolocation range of the dolphin had little effect on his echolocation performance, while continuous noise and noise within the dolphin’s echolocation range decreased performance at a farther distance,” said researcher Eryn Wezensky in a press release. However, Wezensky noted that Gaussian noise, a statistical noise outside the dolphin’s echolocation range, decreased his ability to hear the echo change.


Hearing loss possibly linked to increased risk of dementia

By André Picard, public health reporter, The Globe & Mail

People who lose their hearing are at an elevated risk of developing Alzheimer’s disease and other forms of dementia, a new study shows. In Fact, researchers calculate that about one-third of dementia risk can be explained by hearing loss, even though the connection is rarely considered. “A lot of people ignore hearing loss because it’s such a slow and insidious process as we age,” said Frank Lin, a researcher at the Center on Aging and Health at John Hopkins Medical Institutions in Baltimore, Md.

What is not clear though, Dr. Lin said, is whether there are changes in the brain that simultaneously affect both memory and hearing, or whether the social isolation that often follows hearing loss speeds onset of dementia. Regardless, he said the findings are exciting because they suggest that hearing loss could be an early warning sign of dementia and that something as simple as fitting a person with hearing aids might delay the onset of the debilitating illness.

The study, published in the Archives of Neurology, involved 639 people aged 36 to 90 participating in the Baltimore Longitudinal Study on Aging, a long-term research project that has been ongoing since 1990. At the outset, 455 participants had normal hearing, 125 had mild hearing loss (hearing 25 to 40 decibels less than others), 53 had moderate hearing loss (41 to 70dB) and 6 had severe hearing loss (more than 70dB). None of the participants had dementia at the beginning of the study period.

Between 1990 and 2008, volunteers underwent annual medical examinations, which included tests of hearing and cognitive ability. During the study period, 58 of the participants developed dementia, including 37 cases of Alzheimer’s disease. Researchers found that those with hearing loss at the beginning of the study were far more likely to develop dementia. Furthermore, the more severe the hearing loss, the greater the risk of dementia. For example, those with severe hearing loss were five times

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