Overtone singing is a vocal technique in which a single performer simultaneously produces a sustained fundamental frequency and one or more clearly audible reinforced harmonics by precise manipulation of the vocal tract resonances. Recent magnetoencephalographic (MEG) evidence demonstrates that overtone-rich auditory stimuli drive a pronounced increase in cortical theta-band power (4–8 Hz) with right-hemispheric lateralization, with stimulus type explaining a large proportion of the variance in hemispheric activation patterns in listeners (Saus, Seither-Preisler, & Schneider, 2025). Independently, a substantial body of neuroscience research has established that theta-gamma cross-frequency coupling (TGC), the phase-amplitude modulation of gamma oscillations (~30–80 Hz) by theta rhythms, is a core mechanism supporting working memory, and that its degradation is among the earliest neurophysiological markers of Alzheimer's disease and mild cognitive impairment (Goodman et al., 2018; Goutagny et al., 2013). Here, I propose that active performance of overtone singing generates a unique neurophysiological state in which theta-dominant auditory self-stimulation co-occurs with gamma-band activation from fine motor control, focused attention, and auditory–motor feedback integration. This simultaneous dual-band engagement may create conditions that enhance theta-gamma coupling endogenously, constituting a form of natural, non-technological cross-frequency neuromodulation analogous to what transcranial alternating current stimulation (tACS) achieves artificially (Kolhoff et al., 2024). The Cytoelectric Coupling Hypothesis (Pinotsis, Fridman, & Miller, 2023), which demonstrates that endogenous electric fields organize neural ensembles from macroscale to cytoskeletal levels with particular efficacy at slow (<8 Hz) frequencies, provides a biophysical mechanism by which strong theta oscillations could serve as a field-level scaffold for organizing gamma-band activity. If confirmed, overtone singing practice could represent an accessible, non-pharmacological intervention with potential neuroprotective benefits for cognitive aging and neurodegenerative conditions.

v3.0 (April 2026): Added Section 5.1 (Toward Empirical Testing) sketching a minimal proof-of-concept protocol with a 2×2 factorial design (active overtone singing × passive overtone listening × active conventional singing × passive conventional listening) and a functionally defined inclusion criterion based on F2–F3 coupling control rather than years of practice. Added Prediction 6 (Moderating Variables) covering acoustic context (natural soundscapes vs. urban noise vs. silence) and contemplative framing as moderators of the predicted effects. Added a sentence in Section 6.4 connecting the contemplative-framing variable to the meditation-and-cognitive-aging literature. Refined the wording of the Saus et al. (2025) effect-size description in the Abstract, Introduction, and Section 3.1 (large proportion of variance, robust effect) to align with what the cited paper explicitly reports. Re-attributed the Phase II OVERTURE trial findings to Seshagiri et al. (2024) and treated Park & Tsai (2025) as a review summarizing this work. Softened the description of the HOPE trial. Removed specific regression values from the Goodman et al. (2018) citation, retaining the qualitative claim that TGC was the strongest predictor of working memory across diagnostic categories. In Section 3.3, separated the heart-rate-variability evidence (Inbaraj et al., 2022; Ghati et al., 2021) from the EEG theta evidence, citing Cahn & Polich (2006) and Lutz et al. (2008) for the meditation-EEG link. New references: Berman, Jonides, & Kaplan (2008); Cahn & Polich (2006); Lutz, Slagter, Dunne, & Davidson (2008).