Evidence Report on the Psychophysiological
Effects of Groove Healing Music
— Effects of Polyrhythm and Spatial Audio Design on the Autonomic Nervous System, Brainwave Activity, and Subjective Well-Being —

1-1. The Scale of Workplace Productivity Loss

According to Japan's Ministry of Economy, Trade and Industry, health-related productivity losses total an estimated ¥19.2 trillion annually^[1]. The majority is attributable to presenteeism — employees physically present but unable to perform at full capacity. Deloitte UK (2020) reported an average return of £5 for every £1 invested in mental health initiatives^[2], while Aetna's mindfulness program demonstrated a productivity gain of 62 minutes per employee per week^[3].

1-2. The Limits of Existing Wellness Interventions

Mindfulness apps, yoga, and meditation training point in the right direction but suffer chronically low workplace adoption. Three structural barriers recur: (1) specialized knowledge or technique is required; (2) sustained willpower is necessary; and (3) dedicated time must be carved from an already full schedule.

2-1. Music and the Reward System: Dopamine Release

Using PET scans and fMRI, Salimpoor et al. (2011) anatomically confirmed dopamine release in the brain's reward system during music listening^[4]. Rhythmic prediction combined with subtle deviations (syncopation) most strongly activated reward pathways — directly supporting the neurological rationale for polyrhythmic design.

2-2. Specific Frequencies and Brainwave Entrainment

Akimoto et al. (2018) demonstrated through EEG that alpha waves (8–13 Hz) increase significantly after five minutes of listening to music containing 528 Hz^[5]. Davidson & Lutz (2008) showed that moderate theta wave increases enhance creativity, intuition, and memory consolidation, with meditators demonstrating measurable neuroplasticity^[6].

2-3. Polyrhythm and Cognitive Function

Fitch & Rosenfeld (2007) demonstrated that complex rhythmic structures simultaneously activate the prefrontal cortex, motor cortex, and auditory cortex without cognitive overload^[7]. The Japan Dementia Care Society (2018) reported polyrhythm-based music therapy improved MMSE scores by an average of 2.3 points^[8]. Fang R et al. (2025), in a study of ~11,000 participants, found active music engagement significantly reduced dementia risk^[9].

2-4. Music and Beta-Endorphin Release

Dunbar et al. (2012) demonstrated that music promotes beta-endorphin secretion, producing pain reduction, euphoria, and immune enhancement^[10]. This provides the neurophysiological basis for groove and explains how music can simultaneously produce arousal and calm.

2-5. Workplace Acoustic Interventions

Lazar et al. (2005) confirmed that 8 weeks of meditation produced measurable physical changes in cortical thickness^[11]. While not a direct study of acoustic intervention, it establishes that repeated contemplative practice can produce neurophysiological change within a relatively short timeframe — providing theoretical grounding for cumulative effects of regular Groove Healing Music sessions.

2-6. Binaural Beats and Theta Wave Induction

Jirakittayakorn & Wongsawat (2017) administered a 6 Hz binaural beat on a 250 Hz carrier tone to 28 participants for 30 minutes^[13]. Theta wave activity increased significantly in the frontal and parietal lobes, producing brainwave patterns approximating experienced meditators — even in non-meditating participants. The carrier tone (250 Hz left / 256 Hz right) generates a 6 Hz perceived beat through the brain's frequency following response (FFR). Groove Healing Music incorporates this binaural beat design as an integrated acoustic component.

2-7. Harmonic Overtone Structure and Meditative Induction

Overtones are frequency components at integer multiples of a fundamental f₀ (2f₀, 3f₀, 4f₀…). Three mechanisms explain why overtone-rich sound facilitates meditative states: (1) multi-band auditory stimulation induces broad-band neural synchrony; (2) the integer-ratio structure provides "stable complexity" to the brain's predictive system, sustaining attention while reducing cognitive load; (3) low-order overtone vibrations stimulate the somatosensory cortex, generating the sensation of sound "landing in the body" — directly corresponding to participant reports of "relaxation reaching the bones and blood" and "bubbles rising from the heart."

2-8. Acoustic Engineering Definition of BTN (Between the Note)

BTN (Between the Note) — one pillar of the ONTSUBU Method developed by ONTSUBU LLC (detailed in Section 3) — is an acoustic engineering implementation of the Japanese aesthetic concept of Ma (間: meaningful silence). While traditional music theory treats silence as absence, BTN treats the timing, duration, and phase of silent intervals as active design variables.

In STFT spectrogram analysis, BTN intervals appear as vertical dark bands — temporary collapses of broadband spectral energy. The re-emergence of harmonic components immediately following this interval maximizes the "prediction error signal" in the auditory cortex, activating the dopaminergic system (Section 2-1) while simultaneously triggering the Default Mode Network (DMN)^[15], facilitating introspection and memory consolidation.

Consistent with Ma, BTN is designed not as complete silence but as a low-energy interval retaining reverb tail and noise floor — ensuring "attentive focus on residual resonance" rather than total signal loss, maintaining continuous theta wave induction consistent with Jirakittayakorn & Wongsawat (2017).

3-0. A Three-Dimensional Model of Music — Theoretical Foundation of ONTSUBU Method

Traditional music theory defines six elements: timbre, rhythm, melody, harmony, form, and dynamics — fundamentally describable within a two-dimensional plane of time and pitch. This framework cannot explain why music "lands in the body," why it generates "spatial depth," or why "silence functions as sound." ONTSUBU Method addresses these phenomena through a three-dimensional model adding overtone structure, phase, and spatial acoustics as a third axis.

3-0-1. Mathematical Definition of Phase and Application to BTN

When sound waves with different phases interfere, they either reinforce (constructive: Δφ = 0, 2π…) or cancel (destructive: Δφ = π, 3π…). BTN exploits phase interference to engineer the moment of sound disappearance — creating a "sound shadow" in which the auditory nervous system processes signal absence while somatic vibration persists.

3-0-2. Fourier Transform as Visualization of the 3D Model

STFT spectrograms enable three-dimensional visualization (time × frequency × energy), with BTN intervals appearing as vertical dark bands. This quantitatively demonstrates how ONS (harmonic particle diffusion), BTN (phase-designed silence), and Groove Healing (polyrhythmic temporal fluctuation) function within the compositional architecture.

3-1. Overview of the ONTSUBU Method

Groove Healing Music is based on the ONTSUBU Method — developed over seven years by Miyuki Tani (Ikuyi Minat), Founder & CEO of ONTSUBU LLC, fusing 17+ years of improvisational performance across 60+ countries with acoustic analysis expertise as a licensed Professional Engineer (Urban Planning, Japan). The method comprises three pillars:

• ONS

  Sound Particle Theory

  Treats sound as "particles," using spatial diffusion, convergence, and reflection as design variables. Combines overtone structure design with temporal reverb evolution to generate textures the brain processes as "natural sound."

• BTN

  Between the Note

  Incorporates the Japanese aesthetic of Ma (meaningful silence) into musical structure. Irregular design of intentional silence induces "focus on sonic resonance," generating deep immersion. Silence functions as a compositional element.

• GH

  Groove Healing

  Intentionally designs polyrhythm and groove to act on the brain's reward system and autonomic nervous system. Core technologies: simultaneous layering of different meters (3/4 × 4/4, etc.) and different BPMs; +3–8ms micro-timing deviations; non-mechanical timing fluctuations derived from human improvisational performance.

3-2. Key Acoustic Design Parameters

3-3. Differentiation from Existing Healing Music

Conventional healing music and instruments commonly used in healing sessions — such as crystal bowls — do not generate rhythmic prediction error, which limits stimulation of the brain's reward system. The core technology of Groove Healing Music is the precise reproduction of human timing variation derived from 17 years of improvisational performance, an inherently irreproducible element that AI generation cannot substitute.

3-3-1. The Neurological Limitations of Existing Approaches

① Nature Sound BGM / White Noise
Nature sounds activate the parasympathetic nervous system and have demonstrated improvements in HRV, anxiety, and stress^[*]. However, because natural soundscapes lack the structure of "rhythmic prediction and deviation," they produce no dopamine release through reward system activation. Without musical groove, there is no pathway to beta-endorphin secretion either. Nature sound BGM remains a passive intervention — it flows, but it does not actively engage the nervous system.

② Crystal Bowls / Singing Bowls
Crystal bowls produce rich overtone structures and have been associated with improvements in mood, anxiety, and blood pressure^[*]. However, their primary mechanism is passive relaxation induction through acoustic pressure and physical vibration — not active stimulation of the brain's reward system. Systematic reviews through 2024 concluded that, due to limited RCT evidence and methodological bias risk, singing bowl therapies cannot yet be recommended at an evidence-based level^[*]. Placebo contributions cannot be excluded, and mechanistic understanding remains an open research question.

③ Binaural Beats (standalone)
Binaural beats have the strongest evidence base for theta wave induction, demonstrating the ability to produce meditative brainwave patterns in non-meditating participants within a short timeframe^[13]. However, standalone binaural beat tracks lack groove and embodiment, meaning no pathway exists for beta-endorphin activation. The experience is one of "brainwaves settling, but no felt sense of the body wanting to move" — limiting the simultaneous realization of arousal and calm. Extended use also raises the concern of neural habituation to a single fixed frequency differential.

3-4. Comparative Table of Neurological Mechanisms

The table below compares the neurological mechanism profiles of the primary healing audio approaches currently on the market. Evaluations are based on peer-reviewed literature and the design principles of Groove Healing Music.

References: Nature sound HRV — Kumpulainen et al. 2025 / Crystal bowl systematic review — PMC 2025, University of Adelaide / Binaural beat theta — Jirakittayakorn & Wongsawat 2017 / Dopamine — Salimpoor et al. 2011 (as theoretical basis for polyrhythm design) / Beta-endorphin — Dunbar et al. 2012 (as theoretical basis for groove design) / ◇ indicates that Groove Healing Music's design principles correspond to prior research, but direct experimental measurement of this specific music has not yet been conducted. ✕ indicates that supporting literature for that mechanism was not identified — not that the effect has been disproven.

4-1. Study Overview

4-2. Primary Measurement Items

The survey measured: (1) meditative state experience; (2) emotional/psychological changes; (3) physical/respiratory changes; (4) cognitive function changes; (5) overall satisfaction; (6) recommendation intent (NPS-analogous); and (7) specific track experiences (open-ended).

4-3. Participant Characteristics

Participants represented diverse ages, occupations, and health backgrounds (20s–50s; entrepreneurs, physicians, editors, professional dancers, practitioners), recruited via voluntary invitation. Sessions were conducted online in personal environments using participants' own devices — offering real-world ecological validity while acknowledging acoustic standardization as a limitation (Section 8).

5-1. Overview of Primary Indicators

5-2. Breakdown of Reported Effects

5-3. Representative Participant Reports (Verbatim)

5-4. Expert Reports

6-1. Cross-Referencing Evidence with Survey Data

6-2. The Effect of the Two-Track Program Structure

The two-track sequence (① introductory → ② groove healing) shows a consistent pattern: Track 1 elicited "bodily awareness" and "surfacing thoughts"; Track 2 generated "deeper immersion" and "dissolution of self-sound boundary." This suggests the sequential design rationale: gradually reducing cognitive load before deep acoustic intervention — consistent with synergistic effects observed with the pre-session journaling protocol.

6-3. A Response to the "Unsustainable Wellness" Problem

A notable finding is that participants reported psychophysical changes without any special preparation, technique, or willpower. The 100% change report suggests effect across diverse participants — not merely among those with particular sensitivity profiles — simultaneously addressing all three participation barriers of existing wellness approaches.

6-4. Repeat Attendance Rate as Evidence of Cumulative Effects

Across sessions of 15–20 participants each, 13 of 38 survey respondents (34.2%) were confirmed multi-session attendees. The estimated repeat rate relative to session scale reaches 60–70%+, with actual figures likely higher given non-responding repeat participants.

This goes beyond satisfaction metrics and can be interpreted as indirect evidence of sustained and cumulative effects. Multiple repeat participants reported cumulative benefits — "went deeper than last time" and "felt more attuned and calibrated" — pointing to possible neuroadaptation through repeated experience. At a time when "failure to sustain" is the defining challenge of wellness initiatives, the fact that Groove Healing Music drives voluntary repeat behavior at high rates is particularly notable for corporate deployment durability.

6-5. Why Other Approaches Cannot Produce the Same Results

The results obtained in this study — 100% psychophysical change reporting and 90.2% meditative state experience — represent a level of outcome that is structurally difficult to achieve with existing healing audio approaches. The reason lies in the inherent limitations of each method.

Nature sound BGM activates the parasympathetic nervous system but, lacking the structure of rhythmic prediction and deviation, generates no active reward system stimulation. Crystal bowls produce somatic resonance through overtone structure but rely primarily on passive relaxation through acoustic pressure — falling short of the simultaneous realization of arousal and calm. Binaural beats are effective for theta wave induction but, without groove or embodiment, have no pathway to beta-endorphin activation, limiting the experiential depth of the intervention.

What distinguishes Groove Healing Music is the integration of all three effective elements, combined with a fourth: micro-timing design derived from 17 years of improvisational performance. This micro-timing maximizes the brain's prediction error signal, triggering dopamine release. The result is the simultaneous activation of relaxation (parasympathetic nervous system, theta waves) and arousal (dopamine, groove) — a state that conventional acoustic interventions cannot replicate. When participants describe the experience as "strangely calming, yet somehow I can focus," they are articulating this dual neural activation.

7-1. A Phased Implementation Model

7-2. Return on Investment Basis

Deloitte UK's "£1 → average £5 return" represents a conservative ROI floor, alongside Aetna's 62-minute productivity gain per employee per week. For Phase 1 (BGM licensing), the absence of incremental labor or training costs means ROI likely exceeds these precedent figures.

The following limitations regarding scientific rigor are explicitly acknowledged.

Future Research Plan

Planned for the next research phase: ① HRV-based quantification of autonomic nervous system effects (Phase 1 in planning); ② objective evidence accumulation through EEG linkage; ③ joint effect measurement with corporate pilot deployment partners; ④ theoretical refinement through collaboration with music theory and neuroscience research institutions.

This report examined the psychophysiological effects of Groove Healing Music through proprietary participant survey data (N=108) and peer-reviewed neuroscience literature. Principal findings: all 108 participants (100%) reported psychophysical change, with 91.5% scoring maximum response and a mean score of 3.90/4.0. These reports are highly consistent with seven neurological mechanisms. The micro-timing design derived from 17 years of improvisational performance constitutes an embodied-knowledge technology irreplaceable by AI-generated music.

In the corporate health management context, Groove Healing Music offers a practical solution to the "failure to sustain" problem — functioning as a passive intervention with zero participation barriers. An estimated repeat attendance rate of 60–70%+ further suggests cumulative neuroadaptive effects beyond single-session outcomes.