Sound and stress on the nervous system

Sound can influence the experience of stress and some physiological responses. Music research shows favorable results on average. Here we relate that evidence to breathing, body stimulation, and autonomic regulation to explain a possible path to rest. R1

The path we propose

We can connect three inputs to the process: listening involves attention and emotion networks; breathing influences parasympathetic cardiac regulation; and body stimulation provides sensory information that can participate in autonomous responses. The point of convergence is the regulation of activation, a plausible way to change the experience of tension. This explanation integrates studies of different interventions; it does not require that a single experiment bring together all the components.

There is specific evidence for the first bridge: a 2026 meta-analysis brought together 24 trials of musical interventions with 1,295 participants and found an average increase in high-frequency power in normalized units of HRV, HFnu, of 7.05 units compared to the control. It is compatible with a change in parasympathetic cardiac modulation. Standard units depend on how power is distributed; they do not describe a total amount of vagal activity. R23

Acupressure offers another entry. A trial with 114 healthy volunteers studied atrial point pressure and found acute changes in HRV, including greater changes in RMSSD compared to the simulated procedure. RMSSD describes variation between consecutive cardiac intervals and is often used as an indicator of cardiac vagal modulation. R32

There are also autonomic results with rhythmic contact or slow caresses on the skin. This broadens the reasoning toward somatosensory stimulation in general, although the effect depends on the stimulus. In one study, both types of contact produced comparable cardiac responses despite differences in perceived pleasure. R30

The inference for a session is that sound, breathing and body contact could contribute by converging routes to a resting experience. Applying pressure or vibration using a tuning fork enters into this reasoning as a hypothesis about sensory stimulation; the correspondence of points, receptors and parameters deserves to be described, rather than attributing everything to a frequency.

From the ear to the networks of emotion and attention

The process begins with a physical transformation: vibrations reach the inner ear and move the structures of the cochlea. Hair cells convert that movement into electrical signals that travel down the auditory nerve to the brain. Listening therefore involves sensory input to the nervous system. R2

The musical experience also involves networks that participate in emotion, reward and interpretation of what is happening. Neuroimaging studies relate music to activity in the amygdala, insula, cingulate regions, hippocampus, and nucleus acumbens. These structures have multiple functions; just because they appear active in an image doesn't mean that one is “turning off stress”. R3

A plausible interpretation is that a stimulus that is pleasant and allows us to sustain attention modifies the emotional experience during listening. The same sound can take on different meanings depending on preferences, memories and expectations. This framework helps to formulate research questions; it alone does not demonstrate a therapeutic outcome from a session with bowls or tuning forks. R3

Two systems that should be distinguished

The stress response includes autonomic and hormonal processes. The autonomic nervous system participates in changes in the heart and other organs through its sympathetic and parasympathetic components. The hypothalamic—pituitary—adrenal axis, known as the HPA axis, constitutes another route: signals such as CRH and ACTH participate in the production of cortisol. R4

Therefore, a perceived reduction in tension, a change in heart rate and a variation in cortisol are not interchangeable results. A trial with 60 healthy women compared relaxing music, the sound of water, and rest before a stress test. It found different answers depending on the indicator: music did not produce the lowest cortisol response, although it favored a faster recovery of salivary alpha-amylase compared to rest. The study illustrates the complexity of attributing an overall reduction in stress to sound. R4

What clinical research provides

De Witte and collaborators synthesized 104 randomized trials with 9,617 participants. They obtained a favorable average effect of d = 0.380 for physiological outcomes and d = 0.545 for stress-related psychological outcomes. These are standardized effect sizes: they allow you to combine scales, but they don't mean “38% less cortisol” or “54% less stress”. R1

The studies brought together different populations, formats and measures. The useful conclusion is that there is evidence of average changes with studied musical interventions. This summary does not establish the duration of the benefit for each person nor does it evaluate the entire Human Instrument process. R1

Rhythm, Breathing and Silence

Sound doesn't always decrease activation. In an experiment with 24 participants, faster times increased cardiorespiratory measures; silent pauses reduced heart rate, blood pressure and ventilation. This helps to understand why intensity and temporal structure matter as much as the instrument. The experiment describes immediate responses, not a treatment for chronic stress. R5

Breathing is another important part. A review of 223 studies on voluntary slow breathing found increases in vagus-mediated indicators of cardiac variability during practice and in subsequent measurements. This evidence corresponds to breathing exercises. When a session brings together sound and breathing, part of an observed response could relate to breathing, and attributing it solely to sound would require an appropriate comparison. R6

What does heart rate variability mean

HRV, for its acronym in English, describes the variation in the intervals between beats. Some measures provide information on cardiac parasympathetic modulation, with a significant influence of respiration and recording conditions. HRV does not directly record all of the functioning of the vagus nerve. [R6, R7]

Nor should the LF/HF ratio be interpreted as a simple measure of “sympathetic-parasympathetic balance”. Billman's physiological review explains why frequency bands do not represent two independent components nor do they allow for direct reading. An isolated graph or measurement requires context. R7

Bowls and Acutonics in this frame

Specific research with bowls offers preliminary results, with methodological limits that we describe on the sleep research page. It's important to identify if a publication studies recorded music, bowls, a meditation practice, or a combination. The plausibility of a hearing mechanism does not replace that comparison.

In a Human Instrument, the individual process brings together sound immersion, Acutonics, breathing or visualization, and silence. We explain it as an integrated experience, whose components can contribute in different ways. The interpretation of traditional Chinese medicine patterns belongs to another framework. The studies cited here do not validate frequency effects on meridians or BioWell's interpretations.

How to evaluate a change more clearly

To investigate an intervention, it would be useful to separate perceived tension, daily functioning and physiological measures, and record how long any changes last. It would also be necessary to describe stimuli, duration, respiration, comparison group and follow-up. This is an evaluation proposal, not a protocol that we claim to have applied or results from our practice.

If you are looking for an explanation of the available support, visit Stress and Rest. To learn about its components, read How We Work.

Authorship

Written by Leonardo Murillo, sound therapist at Human Instrument. It is not a medical review or a peer review.

References

• R1 — De Witte and collaborators, 2020. Effects of music interventions on stress-related outcomes: a systematic review and two meta-analyses. Health Psychology Review. Article and summary. DOI: 10.1080/17437199.2019.1627897.
• R2 — NIDCD. How do we hear? Explanation of auditory transduction.
• R3 — Koelsch, 2014. Brain correlates of music-evoked emotions. Nature Reviews Neuroscience. Article. DOI: 10.1038/nrn3666.
• R4 — Thoma and collaborators, 2013. The Effect of Music on the Human Stress Response. FOR THE ELEVEN. Full text. DOI: 10.1371/journal.pone.0070156.
• R5 — Bernardi and collaborators, 2006. Cardiovascular, cerebrovascular, and respiratory changes induced by different types of music in musicians and non-musicians: the importance of silence. Heart. Full text.
• R6 — Laborde and collaborators, 2022. Effects of voluntary slow breathing on heart rate and heart rate variability: A systematic review and a meta-analysis. Neuroscience & Biobehavioral Reviews. Summary. DOI: 10.1016/j.neubiorev.2022.104711.
• R7 — Billman, 2013. The LF/HF ratio does not accurately measure cardiac sympatho-vagal balance. Frontiers in Physiology. Full text. DOI: 10.3389/fphys.2013.00026.
• R23 — Zhang and collaborators, 2026. Effect of music intervention on heart rate variability: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Psychology. Full text. DOI: 10.3389/fpsyg.2026.1750786.
• R30 — Experimental study. Slow stroking evokes a more pleasant sensation but similar autonomic nervous system response than rhythmic touching. Biological Psychology. Summary. DOI: 10.1016/j.biopsycho.2024.108957.
• R32 — Randomized Trial, 2024. Enhancing Vagal Tone, Modulating Heart Rate Variability with Auricular Acupressure at Point Zero: A Randomized Controlled Trial. Medical Acupuncture. Full text. DOI: 10.1089/acu.2024.0001.