The acoustic sensitivity of Autism Spectrum Disorder (ASD) individuals highly impacts their intelligibility in noisy urban environments. In this Letter, the disturbance sensing level is examined with perceptual listening tests that demonstrate the impact of their append High Internal Noise (HIN) profile on intelligibility. This particular sensing level is then proposed as additional aid to ASD diagnosis. In this Letter, a novel intelligibility enhancement scheme is also introduced for ASD particular circumstances. For this proposal, harmonic features estimated from speech signal frames are considered as center frequencies of auditory filterbanks. A gain factor is further applied to the output of the filtered samples. The experimental results demonstrate that the proposal improved the acoustic intelligibility of ASD and Neurotypicals (NT) people considering four acoustic noises at different signal-to-noise ratios.