en Cognitive Neuroscience Cognitive Neuroscience Original Original <div style="text-align: justify;"><span style="font-size:14px;"><span style="font-family:Tahoma;"><span style="line-height:2;"><b>Background</b>: Low-frequency acoustic stimulation can entrain brain oscillations, yet most studies have emphasized gamma-range auditory inputs. The region-specific cortical effects of <i>sub-gamma</i> low-frequency pitch tones in healthy adults remain largely unexplored, and safety concerns persist due to historical reports of adverse effects at high intensities.<br> <b>Objective</b>: To characterize safe, sub-threshold, low-frequency pitch&ndash;induced modulation of cortical oscillations and connectivity using EEG in healthy adults.<br> <b>Methods</b>: Twenty adults were exposed to pure tones (30, 45, and 60 Hz) at intensities <40 dB SPL; well below thresholds associated with adverse neurological effects, under controlled laboratory conditions. EEG was recorded from 8 strategically placed electrodes (covering frontal, parietal, occipital, and temporal regions) using the international 10&ndash;20 system, enabling targeted region-of-interest (ROI) analysis while minimizing noise and redundancy. Power spectral density and alpha-band phase-locking values (PLVs) quantified spectral and connectivity changes.<br> <b>Results</b>: Safe-level low-frequency stimulation elicited region-specific increases in alpha and theta power in frontal, parietal, and occipital cortices (p < 0.05), particularly at 30&ndash;45 Hz. Alpha-band PLVs showed enhanced frontal&ndash;parietal, frontal&ndash;occipital, and parietal&ndash;occipital coupling (p < 0.05). Pitch and exposure duration significantly predicted oscillatory changes (p = 0.0018).<br> <b>Conclusion:</b> Contrary to prior studies linking low-frequency sound to risk at high intensities, our findings demonstrate safe, targeted neuromodulation at sub-threshold levels, revealing frequency-specific entrainment patterns with potential cognitive and therapeutic applications.</span></span></span></div> Low-frequency pitch stimulation, EEG spectral analysis, Cortical oscillations, Alpha-band connectivity, Functional connectivity, Auditory neuromodulation 0 0 http://bcn.iums.ac.ir/browse.php?a_code=A-10-8303-1&slc_lang=en&sid=1 Osagie Odigie odigie.mike@edouniversity.edu.ng 13700319475328460057005 13700319475328460057005 Yes Department of Physiology, Edo University Iyamho, Ogbida, Nigeria. Ugochukwu Bond bond.ugodhukwu@unn.edu.ng 13700319475328460057006 13700319475328460057006 No Department of Physiology, Enugu Campus, University of Nigeria, Nigeria. Daniel Nwachukwu daniel.nwachukwu@unn.edu.ng 13700319475328460057007 13700319475328460057007 No Department of Physiology, Enugu Campus, University of Nigeria, Nigeria. John Igweh jcigweh@gmail.com 13700319475328460057008 13700319475328460057008 No Department of Physiology, University of Delta, Nigeria. Alexander Naiho aonaiho@delsu.edu.ng 13700319475328460057009 13700319475328460057009 No Department of Physiology, University of Delta, Nigeria.