Cognitive Neuropsychology · 2004 · 166 citations · 44 references
EducationAudiologySpeech-language PathologyCommunication DisordersLanguage DevelopmentLearning DisabilitiesAuditory DevelopmentAuditory DiscriminationAuditory Processing DisordersDevelopmental Language DisorderLanguage DisordersLanguage ImpairmentAge-related Auditory Processing ChangesAuditory Cortex DevelopmentAuditory Cortex ProcessingAuditory Evoked Potential DevelopmentAuditory Information Processing DevelopmentDevelopmental Auditory ProcessingFrequency DiscriminationFrequency Discrimination Development
Developmental language and literacy disorders are thought to stem from low‑level auditory perceptual deficits, yet evidence has been inconsistent. The authors aimed to determine whether the inconsistent evidence could be due to heterogeneity within the SLI population. Experiment 2 measured auditory event‑related potentials to unmasked tones in the same SLI and control groups. The study found that a subset of children with SLI showed poorer frequency discrimination and younger age, with ERP data revealing immature N1‑P2‑N2 waveforms, indicating delayed auditory cortex development and later attainment of adult‑level frequency discrimination.
An influential theory attributes developmental disorders of language and literacy to low-level auditory perceptual difficulties. However, evidence to date has been inconsistent and contradictory. We investigated whether this mixed picture could be explained in terms of heterogeneity in the language-impaired population. In Experiment 1, the behavioural responses of 16 people with specific language impairment (SLI) and 16 control listeners (aged 10 to 19 years) to auditory backward recognition masking (ABRM) stimuli and unmasked tones indicated that a subgroup of people with SLI are less able to discriminate between the frequencies of sounds regardless of their rate of presentation. Further, these people tended to be the younger participants, and were characterised by relatively poor nonword reading. In Experiment 2, the auditory event-related potentials (ERPs) of the same groups to unmasked tones were measured. Listeners with SLI tended to have age-inappropriate waveforms in the N1-P2-N2 region, regardless of their auditory discrimination scores in Experiment 1. Together, these results suggest that SLI may be characterised by immature development of auditory cortex, such that adult-level frequency discrimination performance is attained several years later than normal.
44