Adults with dyslexia have problems with non-speech sounds too

June 1, 2010 by Lin Edwards report

(PhysOrg.com) -- Dyslexia is usually associated with persistent reading, spelling, and sometimes speech difficulties that are hard to overcome. One theory proposed to explain the condition is that people with dyslexia suffer from a more fundamental deficit in auditory processing than just interpretation of the spoken or written word, but this idea has produced much debate. Now scientists in Europe have shown that adults with dyslexia do have a specific auditory processing impairment that is not specific to speech sounds.

Dyslexia is a that can hinder the development of spoken and/or written . In visual there is a tendency to reverse letters or numbers and to struggle with writing symbols in the right order. In auditory dyslexia sounds may not be heard correctly or may seem jumbled. There have been many theories about the possible causes of the condition, and much debate about whether the condition only involves comprehension of language or lies in problems with auditory processing in general.

A team of scientists from Belgium, Switzerland and the UK designed experiments that tested auditory dyslexic adults (and non-dyslexic controls) using carefully controlled sound stimuli. They played recordings of consonant and vowel sounds in both speech and non-speech versions, and determined how well the subjects understood the sounds.

For consonants, they played a recording that rapidly alternated between the sounds “ba” and “da,” in a speech version and then in a non-speech version that altered the pitch of parts of the sound, and mixed them up. For example, a non-speech version of “ba” could start with a high-pitch “b” and end with a low-pitch “ah,” or vice versa. They then repeated the experiments with speech and non-speech versions of the vowel sounds “u” and “y”.

The results showed that the subjects with dyslexia did find it difficult to distinguish between consonants but fared as well as the non-dyslexic subjects with vowel sounds. The non-dyslexic subjects had little trouble distinguishing the non-speech versions of the consonants but those with dyslexia were confused by them even if the non-speech tones were only slightly unnatural, which suggests their problem may be a difficulty in processing variations in intonation in sounds, whether from speech or other sources.

The results of the experiments may mean people with dyslexia could be able to undergo auditory training to help them learn to distinguish consonant sounds better by focusing on shifts in pitch.

The paper is published in the Proceedings of the National Academy of Sciences.

More information: Adults with dyslexia are impaired in categorizing speech and nonspeech sounds on the basis of temporal cues, PNAS, Published online before print May 24, 2010, doi:10.1073/pnas.0912858107

Related Stories

Recommended for you

New approach helps rodents with spinal cord injury breathe on their own

October 17, 2017
One of the most severe consequences of spinal cord injury in the neck is losing the ability to control the diaphragm and breathe on one's own. Now, investigators show for the first time in laboratory models that two different ...

Pair of discoveries illuminate new paths to flu and anthrax treatments

October 17, 2017
Two recent studies led by biologists at the University of California San Diego have set the research groundwork for new avenues to treat influenza and anthrax poisoning.

New method to measure how drugs interact

October 17, 2017
Cancer, HIV and tuberculosis are among the many serious diseases that are frequently treated with combinations of three or more drugs, over months or even years. Developing the most effective therapies for such diseases requires ...

A new compound targets energy generation, thereby killing metastatic cells

October 17, 2017
Cancer can most often be successfully treated when confined to one organ. But a greater challenge lies in treating cancer that has metastasized, or spread, from the primary tumor throughout the patient's body. Although immunotherapy ...

Research finds that zinc binding is vital for regulating pH levels in the brain

October 17, 2017
Researchers in Oslo, Norway, have discovered that zinc binding plays an important role in the sensing and regulation of pH in the human brain. The findings come as one of the first studies that directly link zinc binding ...

Researchers find factor that delays wound healing

October 17, 2017
New research carried out at The University of Manchester has identified a bacterium—normally present on the skin that causes poor wound healing in certain conditions.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

dsanco
not rated yet Jun 08, 2010
Another concept that needs to be looked into is the trouble dyslexics may have with interpreting left and right into language...

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.