N100 as a Neural Marker of Atypical Early Auditory Encoding in Autism: Sensitivity to Pitch, Distance-Based Intensity, and Spatial Location

Background Individuals with Autism Spectrum Disorder (ASD) show atypical auditory perception. The N100 event-related potential (ERP) reflects early auditory encoding, predictive coding, and sensory gain. Therefore, this study examined N100 responses to speech stimuli as a neural marker of auditory processing differences in ASD. Methods Event-related potentials (ERPs) were recorded using OpenBCI in 12 boys diagnosed with Level 1 ASD (requiring minimal support) and 15 typically developing (TD) peers. Participants passively listened to Romanian sentences systematically varied in pitch (normal, high, low), distance-based intensity (0.5, 1, 2 meters; 65, 59, 53 dB), and spatial presentation (binaural, left, right). N100 amplitudes and latencies were analyzed using Python and SPSS. Results ASD group indicated significantly reduced N100 amplitudes for normal-pitch stimuli ( p = .030, η² = .175) and binaural presentation ( p = .030, η² = .175). Marginal reductions were also observed for low pitch ( p = .096, η² = .120), speech presented from a 0.5-meter distance ( p = .058, η² = .147), and unilateral conditions ( p s = .066–.077, η²s = .130–.142). No group differences emerged for N100 latency. These findings suggest attenuated early auditory responses in ASD to both typical and spatially complex speech cues. Conclusions Results support predictive coding models proposing reduced sensory precision in ASD. The consistent amplitude attenuation, including near-significant findings, points to subtle but pervasive impairments in early auditory encoding. The use of ecologically valid speech stimuli and portable EEG underscores the translational potential of N100 as a biomarker for early identification and intervention in autism.