Journal of Robotics, Networking and Artificial Life
Vol. 7(2); September (2020), pp. 142–145
DOI: https://doi.org/10.2991/jrnal.k.200528.015; ISSN 2405-9021; eISSN 2352-6386
https://www.atlantis-press.com/journals/jrnal

Research Article

Method of Extracting Sensibility from Time Series Data andConverting it to Vibrotactile
Yasuhiro Suzuki*
Department of Complex Systems Science, Graduate School of Informatics, Nagoya University, Furocho, Chikusa, Ngoya City 464-8601, Japan

ARTICLE INFOABSTRACTArticle History

We propose a method to convert sensory information into non-contact tactile sensation by vibrating of very low-frequency
sound. The vibrator does not directly touch the object in a non-contact tactile sensation. Then, the object vibrates with theextremely low frequency. Previous research has shown that the resonance frequency of the chest and abdomen is about 10 Hz.
Therefore, the chest and abdomen can vibrate in a non-contact manner by using the extremely low frequency of about 10 Hz.
Until now, very low frequencies have hardly used in engineering. We propose new uses for embedding very low frequencies insound such as a music; we name it the deep micro vibrotactile (DMV).

Received 11 November 2019
Accepted 22 May 2020
KeywordsTactile Score
non-contact tactile
low-frequency sounds
deep micro vibrotactile© 2020 The Authors. Published by Atlantis Press SARL.
This is an open access article distributed under the CC BY-NC 4.0 license (http://creativecommons.org/licenses/by-nc/4.0/).

1. INTRODUCTION
In researches of tactile physiology or tactile effects on touch surfaces,
the concept of time development of tactile sense has not considered[1]. While, music is time development in auditory stimuli caused bysound. If the frequency of sound does not change, it is a single tone.
The most of haptic engineering and tactile material researches
deal with tactile senses do not change over time [1]. So, no tactile
materials such as changing touch surface while touching. The only
tactile engineering utilize time development is massage. Massage is
not a single tactile stimulus, but multiple tactile stimuli changing
over time. We have been using massage since ancient [2], one ofthe oldest records of massage is a wall painted on the tomb of an
Egyptian doctor in BC [2].
The progress of hearing is remarkable compared with the senseof touch. A music score has been used since BC to describe thetime-varying sound. The prototype of the musical score used today
was invented by Guido D’Arezzo [3], an Italian priest in the Middle
Ages. While, we cannot know how to do massage by the paint-wallof the doctor’s grave in Egypt cannot, but we can know how to play
the music, which is written by Guido D’Arezzo.
Recent researches have pointed out that, compared with visualsense, the tactile sense is even more essential factors evoking thefeeling of experience [4]. And also, it has indicated that tactile
sense has “language”; for example, the investigation of tactile communication in professional basketball games of National Basketball
Association shows that tactile communications such as high fives
and fist bumps increase the performance of the team and dedicate
to wins or loses [5].
Email: ysuzuki@nagoya-u.jp; www.ysuzuki.info*Although it has indicated that tactile sense might have “language”,
it is still obscure. Hence, we proposed the Tactile Score, which is amethod of time-varying tactile sense. To compose Tactile Score [6],we investigated methods of massages, because massage is the only
tactile engineering method using time-varying.

1.1. Tactile Score
Since there are various elements in the tactile sense, it is not easy
to describe them all. While music also has multiple factors, but themusic score specifies only the pitch and duration. Tactile Score represents only the strength of vertical pressure and length of pressure
and ignores other aspects. Tactile Score generally uses a staff notation, where the third line indicates the “normal strength”; ascending is weak, descending is intense pressure. The length is describedusing musical notes (Figure 1). The normal strength is not absolutepressure, and it should be different in each system or person. Tactile
Score denotes the relative strength from the normal strength.
To use a stuff notation, we divide the difference between the maximum
and minimum pressure into five or seven steps. This dividing is forconvenience, and this number of divisions has no essential meaning.
Since Tactile Score can describe the time-varying tactile sensation,
arbitrary messages can be represented, and it is possible to investigate how to construct massages that were previously unknown. So,
we obtained the principle of the construction method of massage [7].

1.2. Tactile Score Vibration
Since massage is performed using human hands, one person can massage only one person, so it is impossible to massage several people

Y. Suzuki / Journal of Robotics, Networking and Artificial Life 7(2) 142–145

Figure 1 | A Tactile Score, where is generally described using staff notation.
The third line in the centre shows normal pressure, the downward, isrelatively forceful, and the ascending is weak. The alphabet shows the strokeof the massage. The capital A stands for, draw a circle on the cheek, H draws acircle next to the corner of the eye. Each suffix of an alphabet indicates handpart used in massage, e.g. the 5 stands for fingertip, 1 is the palm, so the A5
illustrates the massage of drawing a circle on the cheek with a fingertip.

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implementing non-contact tactile. Human audible frequencies are above 20 Hz and below are non-audible frequencies.
The resonance frequency of the human chest and belly is about
10 Hz. Therefore, the human breast and abdomen can bevibrated by a non-audible ultra-low frequency of about 10 Hz
without touching.
The minimum frequency generated by the pipe organ is 16 Hz,
which is non-audible sounds. However, in Buch’s “Toccata andfugues” this 16 Hz lowest note is used. Such very low-frequency
sound can reach to the distant place. For example, in the Edo
period (1603–1868) in Japan, the time of noon was signaled withsignal cannon everyday form Edo Castle [8] (the Imperial Palacenow). The sound of this cannon all reached above Edo, because thesound of the cannon was transmitted farther by non-audible very
low-frequency sound.
The very low-frequency has not received much attention except
for noise engineering. In noise engineering, insulation of very
low-frequency sound has mainly performed.

Figure 2 | Significant example. The collagen index of pre (left) is 37, while
after (right) is 55. Compared with before (pre) black region is enlarged in after(post), it indicates dermal collagen aggregated toward surface of the skin.

at the same time as music. Besides, to conduct experiments, humans
must perform the massage; hence, it is impossible to generate the sametactile stimulus repeatedly, no matter how proper the technique is.
Because of Tactile Score describes the time change in pressure
intensity and length over time, we can convert a Tactile Score to avibrotactile by changing the amplitude and duration of a vibrotactile according to the Tactile Score.
We call such vibrotactile as Tactile Score Vibration (TSV). TSV candigitize the tactile sensation via Tactile Score. TSV has applied tomany fields such as beauty (Figure 2) and healthcare, and social
implementation is progressing.
By giving a TSV with Haptic Vibration Display, we observed dermal
collagen aggregation in the facial skin by using the DermaLab™
(Cortex Technology Inc.). The number of patients is six and36.7 ± 5.54 years old females. We examined the collagen score,
which indicates the density of dermal collagen, before and after
giving TSV. The average (standard deviation) of collagen score ofbefore giving TSV is 40.8 (5.1), after is 49.3 (4.6). We did the paired
t-test and confirmed that TSV increased dermal collagen statistically significant (p-value was 0.014), where the optimal sampling
number is 7, so N = 6 is close to optimal sampling [7,11].

2. NON-CONTACT TACTILE SENSE
Non-contact tactile sensation is to vibrate an object without
touching it directly. We use the very low-frequency sound forMany studies have done on the effects of infrasound on health[8,9]. However, there are no specific uniform standards because
there are significant individual differences. The Japanese Ministryof the Environment has established a reference standard for low
frequency sounds [9]. According to it, at 10 Hz, if it exceeds
92 dB, it may affect the mind and body. In this study, we use
low-frequency sounds that are less than 1/2 dB of the reference
standard. Regarding human experiments, it has approved by theExperimental Ethics Committee of Nagoya University.

2.1. 40 Hz Vibrotactile Suppresses
Alzheimer Disease
In April 2019, a neuroscientist at the Massachusetts Institute ofTechnology, MIT in the United States found that hearing 40 Hzto Alzheimer rats reduced amyloid-beta accumulation [10],which means that they showed 40 Hz suppressed the progress of
Alzheimer’s disease. They surveyed several frequencies and foundthat 40 Hz was the most effective.
There are no effective treatment for Alzheimer’s disease, andno new drugs have successfully developed. Hence 40 Hz is apromising candidate treatment; 40 Hz is not inaudible sound forhuman, it is a sound close to a vibration whose pitch is almost
unrecognizable.

3. TACTILE SENSE EMBEDDED SOUND
In music, since low-frequency sounds can distort the music, they
were carefully removed. On the other hand, Goro Noguchi, anational singer, has been interested in very low-frequency sound.
He has discovered from years of experience that recognition ofvibrations (very low frequencies) can deliver singing voices far.
Although music and vibration cannot coexist, he has succeeded incoexisting music and vibration using acoustic technology. Throughjoint research with him, we are developing technology to incorporate very low-frequency sound into music, Deep Micro Vibrotactile(DMV) (Figure 3).

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4. CONCLUSION
Haptic engineering has been dealing with tactile sensations delivered by contact. Acoustics has studied audible sounds. Therefore,non-contact tactile and non-audible sounds have not treated. This
research proposes a method to evoke tactile sensation by vibrating by delivering low frequency to the body and suggests a new
method that fuses non-contact tactile and non-audible sound.
It has confirmed that low frequency inhibits the progression of
the pathology of Alzheimer rats and biological responses such as
collagen aggregation. Such low frequencies can be embedded inmusic by Deep Micro Vibrotactile, DMV. In the future, DMVs will
expand across fields, such as the beauty, medical, healthcare, andentertainment industries.

CONFLICTS OF INTEREST
The author declares no conflicts of interest.

ACKNOWLEDGMENTS

Figure 3 | (Top) When only music from the sound exciter gives a soundof music to the container filled with water. (Bottom) When a sound ofmusic, which is synthesized with very low frequency sound is applied(non-audible low frequency) is used. The water vibrates due to the very
low frequency of sound contained in music, and causes ripples.

Figure 4 | Example of synthesizing a music with a very low frequency
sound.

3.1. Very Low-Frequency Sound
Synthesis in Music
When a music synthesized with DMV (Figure 4) reaches to thebody, the audible component shakes the eardrum, and the low-­frequency component vibrates the body. We did experiments inconcert halls and confirmed that DMV can change the tactile quality of sound in live performance.

The authors would like to thank Dr. Mayumi Kotani and Akihito
Fujita, president of Bloom Classic Inc. for their experimentson collagen aggregation for TSV. We would also like to thank
Mr. Goro Noguchi for his various cooperation in the collaboration of DMV.

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AUTHOR INTRODUCTION
Dr. Yasuhiro Suzuki
He is an Associate Professor of Graduate
School of Informatics, Nagoya University
Japan. Graduated from Japan Advanced
Institute of Science and Technology in
1995, received D. Informatics from Kyoto
University in 2001.

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