Feasibility of High-Intensity Low-Frequency Auditory Stimulation in Sedated Non-Human Primates Using Portable EEG and OAE Recordings: A Pilot Study

Background High-intensity low-frequency (HILF) auditory stimulation holds emerging potential for passive neuromodulation. However, its procedural feasibility using portable EEG and otoacoustic emission (OAE) systems in non-human primates has not yet been systematically investigated. Objective This study aimed to evaluate the practical feasibility of administering HILF auditory stimulation in sedated Macaca fascicularis, while simultaneously capturing neurophysiological responses using portable EEG and OAE instrumentation. Methods Two adult macaques were each exposed to 10, 40, and 80 Hz sinusiodal stimuli (110–140 dB SPL) under ketamine-xylazine or propofol sedation. Six predefined progression criteria were applied to assess feasibility: (1) timely recruitment (< 4 weeks); (2) electrode impedance < 5 kΩ; (3) ≥ 90% artifact-free EEG baseline epochs; (4) ≥ 90% EEG and ≥ 95% OAE data capture; (5) equipment precision (± 2 dB, ± 0.5 Hz); and (6) session duration < 120 minutes with no serious adverse events. Results All feasibility criteria were successfully met. Electrode impedance remained within acceptable limits, and EEG baseline quality achieved 92% artifact-free epochs. Data capture rates were 98% for EEG and 96% for OAE, with equipment accuracy maintained throughout. Sessions averaged 105 minutes, with no serious adverse events and only one mild transient discomfort observed. Spectral EEG analysis demonstrated stimulus-evoked modulations in α and β frequency bands, while OAE recordings revealed lateralized amplitude shifts without evidence of cochlear injury. Conclusion The protocol proved fully feasible for delivering HILF auditory stimulation in sedated non-human primates, utilizing portable EEG and OAE devices. All progression criteria were met, and the study yielded interpretable neurophysiological responses. These findings support advancement to larger pilot cohorts and encourage further translational exploration of passive acoustic neuromodulation as a minimally invasive neurotechnology.