title: Atypical vertical sound localization and sound-onset sensitivity in people with autism spectrum disorders.
abstract: BACKGROUND
  Autism spectrum disorders (ASDs) are associated with auditory hyper- or hyposensitivity; atypicalities in central auditory processes, such as speech-processing and selective auditory attention; and neural connectivity deficits. We sought to investigate whether the low-level integrative processes underlying sound localization and spatial discrimination are affected in ASDs.
  
  
  METHODS
  We performed 3 behavioural experiments to probe different connecting neural pathways: 1) horizontal and vertical localization of auditory stimuli in a noisy background, 2) vertical localization of repetitive frequency sweeps and 3) discrimination of horizontally separated sound stimuli with a short onset difference (precedence effect).
  
  
  RESULTS
  Ten adult participants with ASDs and 10 healthy control listeners participated in experiments 1 and 3; sample sizes for experiment 2 were 18 adults with ASDs and 19 controls. Horizontal localization was unaffected, but vertical localization performance was significantly worse in participants with ASDs. The temporal window for the precedence effect was shorter in participants with ASDs than in controls.
  
  
  CONCLUSIONS
  The study was performed with adult participants and hence does not provide insight into the developmental aspects of auditory processing in individuals with ASDs.
  
  
  CONCLUSIONS
  Changes in low-level auditory processing could underlie degraded performance in vertical localization, which would be in agreement with recently reported changes in the neuroanatomy of the auditory brainstem in individuals with ASDs. The results are further discussed in the context of theories about abnormal brain connectivity in individuals with ASDs.
authors.affiliation: Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, and Department of Cognitive Neuroscience, Nijmegen, the Netherlands.
authors.forename: Eelke
authors.initials: E
authors.lastname: Visser
authors.forename: Marcel P
authors.initials: MP
authors.lastname: Zwiers
authors.forename: Cornelis C
authors.initials: CC
authors.lastname: Kan
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Hoekstra
authors.forename: A John
authors.initials: AJ
authors.lastname: van Opstal
authors.forename: Jan K
authors.initials: JK
authors.lastname: Buitelaar
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002659:Child Development Disorders, Pervasive / Q000523:psychology*; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D008297:Male; D013017:Sound Localization