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A Research Report by Dr Yewande Pearse
What does it mean to be relaxed? Most people tend to think it means feeling calm and free of tension, stress or worry. But achieving true, physiological relaxation requires even more than that. To be physically relaxed, you need to relax your muscles, find a quiet environment, focus your attention, let go of goal-orientated analytical thinking, and be receptive to unusual feelings of relaxation. If you’ve ever been to a guided meditation class, you may have noticed that some form of sound was playing gently in the background. This is because most relaxation methods use external objects of focus, which help re-direct external attention to internal attention, and promote self-reflection. Music, especially relaxing music, is a common example of an external cue that can be used to enhance relaxation.
However, music is not the only type of external relaxation aid. Sensory stimulation with a body monochord, during which vibrations can be physically felt, add an additional external focus. A body monochord is a resonance box on four feet. Below the sound box, there are approximately 60 strings, which can be tuned to different pitches. A practitioner sits next to the body monochord, stroking evenly across the strings with the fingers of both hands, creating a sound and vibration. When someone makes contact with the resonance box, they are able to directly feel the vibration along with the acoustic sound produced. Studies from the nineties and early 2000s have shown that, when people sense vibration and sound produced by the body monochord, they can experience deep states of relaxation. Yet, how this kind of audio experience actually affects brain activity and brings about relaxation and stress reduction is a bit of a mystery. However, more recently, scientists have made progress in figuring out how vibroacoustic stimulation (or sound accompanied by physical vibration) and conventional relaxation music change brain activity.
To find out how vibroacoustic stimulation with a body monochord is different from music alone, Hubertus Sandler and other researchers in Berlin used an electroencephalogram (EEG) test to record brain activity. During an EEG recording session, small sensors are attached to the scalp to pick up the electrical signals produced when brain cells send messages to each other. This test is used in hospitals to detect seizures, epilepsy and head injuries but can also reveal how the brain responds to a stimulus. EEG data is shown as wave patterns, which can be grouped according to their frequencies. Alpha brainwaves are characterized by frequencies between 9 to 14 cycles per second, and can be observed when listening to music within the context of relaxation and introspection. The next state, theta brainwaves, are typically of greater amplitude and slower frequency, and this frequency range is normally between 5 and 8 cycles per second. Theta brain waves are associated with the concentrative focus on a mental stimulus, needed during meditation and relaxation.
As part of their experiment, Sandler and his group worked with 60 male and female patients with depressive disorder, anxiety disorder or adjustment disorder. The researchers started out by getting a baseline reading of brain activity with a two minute resting EEG recording. Each patient received 2 treatments: first, a 20 minute exposure on a body monochord with 64 strings producing various pitches; second, a 20 minute presentation of relaxing music from a CD (“Clouds” by Canzani). Between the experiments, patients filled out a questionnaire on their experience during the previous treatment. The scientists took EEG measurements three different times during the 20-minute session, and picked out the theta and alpha frequency bands (divided into Alpha-1and Alpha 2).
Once all the data had been collected, the researchers separated the patients into three groups according to the intensity of their positive emotions during the treatments (rated from 0 to 6, with 6 being a highly enjoyable experience). When Sandler and his team analysed the EEG recordings, they discovered that changes in brain waves depended on the intensity of positive emotions and differed between the two kinds of treatments. Theta activity increased over time during monochord treatment, but the effect was greater in patients who reported really liking the experience. Alpha brain activity, on the other hand, was a little more complicated. Alpha-1 brain activity didn’t increase consistently across the patients and those who really liked the body monochord showed lower Alpha-2 brain activity.
So how did this compare with brain activity when the patients were just listening to Canzani? Although wave frequencies changed over time, the intensity of positive emotional feelings had no effect. Meaning, that theta waves, associated with the relaxation state, become greater during the course of monochord treatment, and overall, compared to CD-music, if the patients like the experience.
Sandler wasn’t just interested in how brain activity was changing during monochord treatment compared to recorded music, but where these changes were occurring. Each section of the brain is associated with different functions. Theta waves in the frontal lobe are linked to focused attention and music-induced emotions. The research team found an increase in theta waves in the frontal lobe, meaning that Sandlers findings were consistent with what we know about brain activity during relaxation and emotion.
Image showing how a positive emotional experience following vibroacoustic stimulation using a body monochord is associated with an increase in EEG-Theta and a Decrease in EEG-Alpha power.
Key: EEG = Electroencephalogram
T2 = EGG taken between 5-7 min
T3 = between 11-13 min
T4 = between 17-19 min) (Averaged for absolute Theta during session)
BM > Mu = People who experienced body monochord in an emotionally more positive way than relaxing music
BM < Mu = People who experienced body monochord in an emotionally less positive way than relaxing music
This study showed that the effects of vibroacoustic stimulation depend on how much the person enjoys the experience. SUBPAC, is like a portable, electronic version of a body monochord, that is able to produce a wider range of sounds. Instead of sound and vibration being generated by the strumming of the strings, the vibration comes from bass sound and the wearer can decide what sound they want that to be. When someone is completely consumed by an activity and loses track of time, scientists say they are in a flow state. That intense involvement in an activity is a possible explanation for the differences observed in the study. The positive emotional experiences associated with the body monochord could be related to this flow experience. To achieve a state of flow, your brain needs to be stimulated, not bored, but still below the threshold for excessive demand. During both physical and auditory stimulation, participants are exposed to a sensory-musical experience that satisfy this criteria; they are not just listening to music, they are getting an additional physical experience that is more stimulating than music alone but is also not too stimulating. Maybe, the scientists suggest, people enjoyed the body monochord, because they were in a flow state. People report all kinds of feelings of well-being when using the SUBPAC, from feeling relaxed and less stressed to feeling a deeper, more intense connection with music. SUBPAC delivers auditory bass sound with physical vibration, creating an enhanced sensory physical-audio experience. Based on Sandlers study, it is possible that when people enjoy this sensation, it can boosts relaxation. It’s important to remember that the data in most of the scientific studies discussed here were collected from patients who had been diagnosed with a mental illness, not the general population. Nonetheless, this research offers a glimpse into how relaxed brain waves are enhanced when music is accompanied by vibration, providing some insight into what makes SUBPAC so effective.
Check out more with Dr Yewande Pearse at https://www.soundsciencepodcast.com/