Rising-frequency chirp stimuli effectively enhance the amplitude and shorten the latency of 40-hz auditory steady-state response.

To evaluate the effects of changes in group delay from a click signal to a chirp signal on the 40-Hz Auditory Steady-State Response (ASSR) using magnetoencephalography (MEG). In this study, each participant was exposed to 10 chirp signals with gradually varying group delays from the CE chirp to the click at 60 dB nHL. The 40-Hz ASSR was measured using MEG and evaluated for amplitude and latency in the maximum signal channel at the click signal measured in each hemisphere. Ten native Japanese speakers without histories of auditory diseases (8 males and 2 females, mean age 28.4 ± 5.70 years) participated in the study. The 40-Hz ASSR amplitude increased with the group delay of the chirp signal, was most efficient with the CE-chirp (longest group delay) and was significantly larger in the contralateral hemisphere for the CE-chirp than with the click signal. No significant differences were observed in ipsilateral hemispheres. The latency of the 40-Hz ASSR decreased as the group delay of the chirp signal increased. This study demonstrated that chirp signals, particularly the CE chirp, are more efficient than click signals in eliciting a 40-Hz ASSR, especially in the contralateral hemisphere.