An Evidence-Based Perspective on "Misconceptions" Regarding Pediatric Auditory Processing Disorder

Detecting Central Auditory Processing Disorders in Awake Mice

Mice are increasingly used as models of human-acquired neurological or neurodevelopmental conditions, such as autism, schizophrenia, and Alzheimer's disease. All these conditions involve central auditory processing disorders, which have been little investigated despite their potential for providing interesting insights into the mechanisms behind such disorders. Alterations of the auditory steady-state response to 40 Hz click trains are associated with an imbalance between neuronal excitation and inhibition, a mechanism thought to be common to many neurological disorders. Here, we demonstrate the value of presenting click trains at various rates to mice with chronically implanted pins above the inferior colliculus and the auditory cortex for obtaining easy, reliable, and long-lasting access to subcortical and cortical complex auditory processing in awake mice. Using this protocol on a mutant mouse model of autism with a defect of the Shank3 gene, we show that the neural response is impaired at high click rates (above 60 Hz) and that this impairment is visible subcortically-two results that cannot be obtained with classical protocols for cortical EEG recordings in response to stimulation at 40 Hz. These results demonstrate the value and necessity of a more complete investigation of central auditory processing disorders in mouse models of neurological or neurodevelopmental disorders.

Speech cortical activation and connectivity in typically developing children and those with listening difficulties

Listening difficulties (LiD) in people who have normal audiometry are a widespread but poorly understood form of hearing impairment. Recent research suggests that childhood LiD are cognitive rather than auditory in origin. We examined decoding of sentences using a novel combination of behavioral testing and fMRI with 43 typically developing children and 42 age matched (6-13 years old) children with LiD, categorized by caregiver report (ECLiPS). Both groups had clinically normal hearing. For sentence listening tasks, we found no group differences in fMRI brain cortical activation by increasingly complex speech stimuli that progressed in emphasis from phonology to intelligibility to semantics. Using resting state fMRI, we examined the temporal connectivity of cortical auditory and related speech perception networks. We found significant group differences only in cortical connections engaged when processing more complex speech stimuli. The strength of the affected connections was related to the children's performance on tests of dichotic listening, speech-in-noise, attention, memory and verbal vocabulary. Together, these results support the novel hypothesis that childhood LiD reflects difficulties in language rather than in auditory or phonological processing.

Evidence of Validity and Normative Values of a New Auditory Backward Masking Test

There are still no valid, clinically feasible instruments to assess backward masking (BM), an auditory temporal processing (ATP) phenomenon. The aim of this study was to develop, standardize and present evidence of validity for a behavioral test for BM assessment. Young adults were submitted to a BM test (BMT), where they were asked to identify a 1000 Hz pure tone followed by a narrowband noise with interstimulus intervals of 0 to 400 ms and signal-to-noise ratio (SNR) between −20 and −30 dB. The correct response rate and target sound detection threshold were calculated, and the results compared with those of young adults with abnormal ATP tests and older adults. Diagnostic accuracy analyses were carried out. Young adults with normal ATP obtained an average correct response rate of 89 and 87% for SNR −20 and −30 dB, respectively, with average thresholds between 10 and 15 ms and no difference between the left and right ears. Results were more consistent at SNR −20 dB, and the best diagnostic accuracy was obtained for SNR −20 dB, with good specificity, but low sensitivity. Normative values were obtained for the BMT, which proved to be clinically feasible, with preliminary evidence of validity.

Speech Perception in Noise Predicts Oral Narrative Comprehension in Children With Developmental Language Disorder

We examined the relative contribution of auditory processing abilities (tone perception and speech perception in noise) after controlling for short-term memory capacity and vocabulary, to narrative language comprehension in children with developmental language disorder. Two hundred and sixteen children with developmental language disorder, ages 6 to 9 years (Mean = 7; 6), were administered multiple measures. The dependent variable was children's score on the narrative comprehension scale of the Test of Narrative Language. Predictors were auditory processing abilities, phonological short-term memory capacity, and language (vocabulary) factors, with age, speech perception in quiet, and non-verbal IQ as covariates. Results showed that narrative comprehension was positively correlated with the majority of the predictors. Regression analysis suggested that speech perception in noise contributed uniquely to narrative comprehension in children with developmental language disorder, over and above all other predictors; however, tone perception tasks failed to explain unique variance. The relative importance of speech perception in noise over tone-perception measures for language comprehension reinforces the need for the assessment and management of listening in noise deficits and makes a compelling case for the functional implications of complex listening situations for children with developmental language disorder.

Validity of the Multiple Auditory Processing Assessment-2: A Test of Auditory Processing Disorder

Purpose A normative study using the Multiple Auditory Processing Assessment-2 (MAPA-2; Schow et al., 2018) was recently completed. With access to these data, the authors extend that work and support a definite construct for auditory processing disorder (APD). The goal here is to examine MAPA-2 reliability and validity (construct, content, and concurrent). Evidence for the APD construct is further buttressed by measures of sensitivity and specificity. Results of MAPA-2 testing on children diagnosed with learning disability (LD), attention-deficit/hyperactivity disorder (ADHD), and specific language impairment (SLI) are included. Method Normative data (previously published as the MAPA-2) allowing derivation of these findings included a representative sample of 748 children (53% girls) ages 7-14 years tested by 54 speech-language pathologists and audiologists in 27 U.S. states. The authors examined diagnostic accuracy based on the American Speech-Language-Hearing Association (2005) criteria (index test) for confirmed cases of APD. The index was also used to identify listening problems for three other diagnostic categories (LD, ADHD, and SLI). Validated questionnaire responses from parents and school personnel allowed incorporation of functional measures widely supported in APD diagnosis but unavailable with other normative and sensitivity/specificity studies. Results Reliability and validity were both satisfactory, and diagnostic accuracy for an APD group of 18 (28% female) compared to the remaining typical group of 625 yielded 89% sensitivity and 82% specificity. The remaining three groups (LD, ADHD, and SLI), where comorbidity was expected to be about 50%, had APD-type listening problems with a prevalence ranging from 52% to 65%. Conclusions Current results provide important evidence for the construct of APD. The MAPA-2 can be administered by an audiologist or speech-language pathologist. A similar diagnostic protocol in Australia yielded positive therapeutic gains. Further study is encouraged to determine if the present positive findings will be found in future research.

Clinical Expertise Is Core to an Evidence-Based Approach to Auditory Processing Disorder: A Reply to Neijenhuis et al. 2019

The opinion article "An Evidence-based Perspective on Misconceptions Regarding Pediatric Auditory Processing Disorder" by Neijenhuis et al. (1) presents a distorted view of the evidence-based approach used in medicine. The authors focus on the amorphous non-diagnostic entity "listening difficulties" not auditory processing disorder (APD) and create confusion that could jeopardize clinical services to individuals with APD. In our perspective article, we rebut Neijenhuis et al. (1), and more importantly, we present a rationale for evidence-based practice founded on the premise that research on APD is only clinically applicable when conducted on clinical populations diagnosed with APD.