Auditory brainstem responses to high-resolution audio sounds: Effects of anti-alias filters

Despite the superior technical specifications of high-resolution audio in comparison to conventional compact discs (CDs) and digital versatile discs (DVDs), whether and how high-resolution audio leads to an improved subjective listening experience remains unclear. The sound quality of conventional digital formats is deteriorated by temporal blur, which is caused by a high-cut filter applied to avoid aliasing of a digital sound source, resulting in spurious artificial sound energy before and after the actual sound onset. Using sound materials of high-resolution audio grade, this study investigated the effects of filter-induced temporal blur on the auditory neural pathway from the cochlea through the rostral brainstem by measuring the auditory brainstem responses (ABRs) of participants with normal hearing. The participants (N = 24) listened to 0.1-ms clicks, with and without a high-cut filter of 22 kHz or 11 kHz applied to them. The amplitudes and latencies of five ABR waves (<10 ms) revealed no significant effects caused by filtering. The participants could not distinguish between the original and the 22-kHz filtered click sounds, while they could distinguish between the original and the 11-kHz filtered sounds. These results indicate that a CD-level anti-alias filter does not affect initial auditory processing and the sound difference is not discernible, at least for artificial sounds with a simple acoustic structure.