Impaired Peripheral Sound Localization Is Associated with Repetitive Behaviors and Sensory Abnormalities in Individuals with ASD

Background: Auditory processing abnormalities are reported frequently among clinical descriptions and experimental findings regarding autism spectrum disorders (ASDs).  Failure to orient to environmental sounds, including to respond to one’s name, is a common feature in ASD, and difficulties with sound localization could contribute to auditory orienting and attention deficits.  However, the ability of individuals with ASD to spatially localize sounds has been remarkably understudied.

Objectives: To evaluate sound localization abilities of individuals with ASD, in comparison to controls, and to examine whether these abilities relate to social, communication, repetitive behavior, and sensory processing symptoms central to the ASD phenotype.

Methods: Participants were 22 individuals with ASD (Mean Age: 19.91 years; Mean IQ: 108.18) and 36 control participants (Mean Age: 16.89 years; Mean IQ: 110.22).  Groups did not differ in age or IQ score (ps = 0.70 and 0.58, respectively). All participants completed a task in which pure-tone beeps (28 kHz) were randomly presented from speakers positioned at 30, 90, and 150 degrees around a 180-degree arc, where the “90-degree” speaker was located directly in front of participants’ heads, at a distance of 1.1 meter. Beeps were presented alone, or with either spatially-congruent or spatially-incongruent visual flashes; for the present study, only trials containing auditory stimuli in isolation are analyzed. Participants used a joystick to indicate the spatial location from which each sound was emitted.  For each participant, mean localization accuracy was calculated at each speaker position as the absolute value of the mean response angle, subtracted from the true speaker position angle.  Between-group differences in localization ability were evaluated using an ANCOVA, covarying for IQ. Parents of participants completed the ADI-R to measure broad diagnostic features, and the RBS-R and SEQ to report in more detail on repetitive behaviors and sensory symptoms, respectively. Partial correlations between spatial localization abilities and parent report measures were conducted, covarying for IQ. 

Results: For localizing auditory cues, individuals with ASD performed less accurately than controls at both peripheral locations: 30-degree, F(2,58)= 2.862, p=.096; 150-degree, F(2,58)= 4.949, p=.030.  No group differences in auditory cue localization abilities were seen for the central (i.e., 90-degree) target (p=.871).  For participants with ASD, poorer auditory spatial localization abilities at the 150-degree location were associated with increased repetitive behaviors on the ADI-R (r= .623, p=.004) and RBS-R (r= .577, p=.008).  Poorer auditory spatial localization skills were also associated with increased sensory hypo-responsiveness (r= -.401, p=.08), sensory seeking  (r= -.568, p=.009), and atypical auditory (r= -.406, p=.076) behaviors on the SEQ.  No correlations with social or communication scores from the ADI-R were observed.

Conclusions: Relative to control participants, individuals with ASD demonstrated impaired spatial localization abilities for auditory stimuli emitted from peripheral locations.  Within the ASD group, more impaired sound localization abilities were associated with increased repetitive behaviors and broad sensory processing abnormalities, but not with social or communication functioning.