The researchers used meta-analysis to reveal hearing processing defects in dysfunction.

Developmental dyslexia (DD) is a particular difficulty in gaining reading skills that cannot be attributed solely to intellectual levels, visual asenssive problems, and poor schooling.
the study of pinyin text suggests that hearing processing defects may be one of the underlying mechanisms that cause DD.
the rapid auditory processing defect theory points out that the rapid change or short-term auditory stimulation of DD processing is defective.
time sampling theory also points out that there are anomalies in the low-frequency phase-locking mechanism of the hearing cortal layer of DD.
-matching negative wave (MMN) can effectively reflect the individual's ability to perceive changes in auditory information.
many studies have used this indicator to examine the auditory processing defects of DD.
using this indicator, most studies have found hearing abnormalities in DD, but some have not.
After analysis, the ineganic in agreement between the studies is mainly reflected in two aspects: first, whether DD's auditory processing defects are speech-specific or general; Recently, the Research Group of Bi Hongyan of the Institute of Psychology of the Chinese Academy of Sciences completed a meta-analysis aimed at quantitatively analyzing the existing literature, answering the above-mentioned controversial questions and clarifying the auditory processing characteristics of DD. The
study included 25 literatures examining the defects of DD auditory processing and divided them into four categories according to age and speech characteristics, namely, children-speech hearing processing, adult-speech hearing processing, children-non-verbal auditory processing, and adult-nonverbal hearing processing.
found that adults and children with DD had less MMN amplitude than normal readers when processing speech auditory stimulation, while only DD adults showed defects under nonverbal auditory stimulation conditions, while children did not.
To explore the causes in depth, the authors distinguished nonverbal stimuli according to the complexity of stimuli, and found that DD adults showed defects only when processing tone patterns stimulation, but none of the studies examining the auditory processing ability of DD children used such stimuli.
the first time, meta-analysis method was used to quantitatively analyze the controversial issues in this field.
results show that speech hearing processing defects in DD do not disappear with age, and DD adults exhibit general auditory processing defects.
This result provides inspiration for future studies that should consider including auditory processing assessment in the diagnosis of DD, and that the exploration of nonverbal auditory abilities in DD children should increase the complexity of stimuli, using nonverbal auditory stimuli similar to verbal auditory stimuli, such as tone pattern stimulation, and that adolescents should be considered a critical stage in the development of auditory processing and should be strengthened in this age group.
research papers have been published online in Neuroscience and Biobehavioral Reviews (116, 396-405).
the study was funded by the National Natural Science Foundation of China.
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