SA-C4-4 SCIS&ISIS2006 @ Tokyo, Japan (September 20-24, 2006)

Does Humming Sound Play Healing Role in Bhramari Pranayama Rajkishore Prasad, Fumitoshi Matsuno Man Machine Interface Lab., University of Electro Communication, Japan E-mail:{kishore,[email protected]}

Abstract—This paper investigates role of humming sound in the healing process by Bhramari Pranayama (BP) which has been recommended, in many literatures on yoga, for removing stress and healing many mental abnormalities and has also been claimed to be recuperative for the same by many practitioners. Pranayama is a Sanskrit word which literally means a yogic act performed for controlling flow of vital energy in the body and mind. One of the main acts during doing BP is that subject imitates humming sound of bumble while exhaling. The analysis of the humming sound produced during pranayama (a) Bumble bee (b) Common bee shows a little variation in pitch confined within lower frequencies with concentration of energy in the lower frequency bands. Nasal Fig.1 Showing black bumble and common bee. Bumble formants are also present. The humming sound has also vibrato. bee can be distinguished by furs on body which is absent It is hypothesized that such sound produces not only bone in the common bee. conducted audition but also vibration in cranium and changes in the brainwave patterns leading to relaxation and healings.

Index Terms— yoga, humming sound, vibro-acoustic, bhramari pranayama.

I. INTRODUCTION HIS paper contains report on preliminary studies on our T project to develop artificial system for mental relaxation based on speech signal patterns of bumble bee. So, at present we cannot say that it comes under biomimetics but our ultimate aim is to reach there. The term Yoga needs no Fig.2 One of the easiest body posture for doing Bhramari introduction. It is well known and practiced all over the world. Pranayama. Subject hums steadily like a bumble bee Yoga has its origin in Indian civilization, nearly 6,000 years while keeping attention at third eye point. ago as a part of Indian healing Science known as Aryuveda. The earliest record of yoga is available in Indian oldest ritual books Bhramari is a Sanskrit word which means like bumble bee, as known as the Veda dating back about 4000 BC, however, it has shown in Fig.1(a), and this pranayama got its name because in been argued by many that yoga emerged as fully developed BP one has to produce or imitate humming sound of the bumble health practice from 500 B.C[1],[2]. There had not been bee while strictly exhaling through nasal cavity keeping oral scientific studies, like nowadays, on the yoga in the deep past cavity closed at the lips. While doing so eyelids are shut down, and thus knowledge about benefits and effects of the yoga has ears are kept closed by fingers or ear flap and concentration is been based entirely on the direct observations for thousands of kept at the third eye point as shown in Fig.2. There are also years and has been documented so. However, in the modern era other ways of doing BP, however, variation is only with body scientific studies have been started on the yoga and results in postures and production of humming sound during exhalation the most of the cases have been found as per subjective claims and inhalation. Descriptions of different ways of doing BP can made by the practitioners [3],[4],[5]. Pranayama is also a type be found in the related texts. BP has been found to be effective of yoga popularly known as Hath Yoga. According to in controlling blood pressure both high and low, reducing Hathyoga Pradipika [6], Hath yoga also leads to Raja Yoga or tension, bringing relaxation, improving condition of ear, throat, Power Yoga and had also been originated in the Indian nose and sinus, reducing cerebral tension, hypertension, civilization thousands of years back. The Sanskrit word anxiety and in healing many other mental problems claimed by Pranayama contains two meaningful segments namely different subjects [6],[7],[8]. However, to the best of our (this means vital force, air) and (this means control). So knowledge, no scientific study on BP has been made so far pranayama literally means a yogic act performed for except in [7] in which author has verified scientifically some of controlling flow of energy in the body and mind. Bhramari the subjective claims without touching the mechanism acting Pranayama (BP) is one of the popular types of pranayama. behind the BP in bringing different changes in the mind and

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body. In [7], it has also been reported that BP is very much sound. The OM sound is again from Veda and has special useful for the pregnant women and preparation for labor. significance as reported in [16]. There are also another ways of BP is different from other pranayamas in the fact that in this making humming sound by pronouncing nasal [n], however, pranayama acoustic vibration is produced by humming sound there is difference in co-articulation and thus spectral contents along with yogic body posture. The acoustic vibration might be of sounds. During pronouncing nasal [m] sound, oral cavity is playing key role in producing effect of BP by vibrating brain closed at lips and resonant frequency component of oral cavity and whole head. In the old literature, it has been mentioned that is not present in the sound outputted at nostrils. While saying BP is supposed to activate the third eye point, the philosophical [m] the oral cavity also resonates but it is closed at lips and eye of wisdom, as concentration is held here during BP. The while saying [n] the length of oral cavity is shortened by third eye point is related with pineal gland and has been specific positioning of the tongue of the speaker. described as the center of imagination, memory, concentration, intuition, deeper knowledge, and ability to visualize the things 0.2656 [9],[10]. In this paper our main aim is to investigate what are the characteristics of humming sound produced during BP and 0 why has it been recommended to hum like a black bumble bee not like an ordinary bee and make some research hypotheses -0.3906 for future investigation with modern scientific techniques. 0 0.24 0.48 0.72 0.96 1.2 Time (s) Rest of the paper is organized as follows. In Section II humming sound and its clinical importance has been described. (a) Speech signal of the common bee Section III contains analysis of the humming sound produced during BP. Section IV contains general discussion and related research issues. Section V contains conclusions and future work which is followed by references.

II. HUMMING SOUND AND ITS CLINICAL IMPORTANCE In the related texts on BP, it has been instructed to imitate (b) Pitch of the sound of common bee. humming sound of black bumble bee while performing it. It seems very natural to say why to hum like a bumble bee and not like a common bee (shown in Fig.1b)? The humming sound of bumble bee is different from the ordinary bee, however, mechanism of sound production is same. The mechanism of sound production in bee has been discovered much before by E.F. Woods and Wenner [11],[12] and has been proposed that bees produce sound by pulsed air stream through seven pairs of spiracles uniformly distributed over abdomen and thorax. These all are tuned to same frequency through muscles causing (c) Spectrogram of sound of common bee wings to flap. The waveform of sound of ordinary bee and bumble bee are shown in Fig.2a and Fig.3a respectively. It can Fig.2 Sound with its pitch and spectrogram of common be imbued from their pitch plots that the sound of bumble bee is bee.(http://www.junglewalk.com/sound/). much steadier and not wavering like that of the common bee. The similar results for the bee sounds has also been reported in [13] under various conditions. In [14], it has been reported that the bumble bee can sound for longer time. As per texts on BP, the humming sound production in BP should also be steady, prolonged and produced with less effort. The spectrograms and power spectrums of sounds of bumble and common bee are shown in Fig.2 and Fig.3 which revel that sound of bumble bee is enriched in low frequency components and its energy is (a) Speech waveform of bumble bee concentrated in the lower frequency bands. Fig.4 compares spectral power of the sound of bumble bee and common bee. It can be imbued from Fig.5 that major part of the total energy in the sound of bumble bee is contained within smaller spectral range (up to 800 Hz) in comparison to that of common bee. In human speech production mechanism is different and production of humming sound like that of bumble bee needs practice to control pitch that depends on many factors [15]. It has been recommended in the texts on BP that the humming (b) Pitch of the bumble bee sound. similar to bee can be produced by sustaining [m] part of the OM

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volume. However, this effect depends on the spectrum of the humming sound. In [19], it has been reported that that the sinus cavity works as the Helmholtz resonator and exchange of NO from it depends on displacement of plugged air in the neck (ostia) of the resonator (sinus cavity). The resonant frequency of the Helmholtz resonator depends on velocity of sound, cross section area and effective length of the air column plugged into the neck (ostia) and the volume of the resonator (here sinus cavity).The resonant frequency of the human sinus (acting as (c) Spectrogram of bumble bee sound. Helmholtz resonator) varies somewhere between 600Hz to 1KHz. It has been reported in [19] that the maximum exchange Fig.3 Sound with its pitch and spectrogram of the bumble of NO depends on the exciting frequency (humming sound) bee. and if it is very near to resonant frequency the exchange of NO is maximum. In summary the humming sound produced will be effective in producing better ventilation of NO if it has low frequency components. In the next section, we will see that the humming sound of BP has low frequency components in domination that better explains healing capacity of BP for the sinus problems. The acoustic vibration produced by humming sound is transmitted into the other parts of head too. However, the transmission of acoustic wave in head is not well understood and very few studies had been made in this direction. In the BP, since ear is closed by fingers the auditory Fig.4 Power Spectrum of sound signal of common bee and effect is reduced, bone conducted sound is contributing to bumble bee sound. audition, and vibratory effect is increased. In [21],[22] it has been reported that resonance frequency of human skull is 800Hz-1.2KHz.The contribution of vibration effect produced by humming sound in relaxation is not known but in the past years there have been many investigations and formulation of postulates for the use and working of sound as the medicine [24],[25] . In this context humming sound in BP can also be seen as playing key role in bringing positive effects on mind and body as the humming sound in BP is highly active and kinetic part. The other distinction of BP from other pranayamas

is that it is quick in effect. It has been documented that do BP Fig.5 Comparison of total energy (TE) content up to and go in the seventh heaven. It is in contradiction to the different frequency band in the sound of common bee and general concept that yoga is not like a quick fix and it takes bumble bee. time to bring effect. In BP effects follow immediately.

Humming by saying sustained [m] will have lower first formant frequency while for [n] it will be higher [17]. Thus production of humming with sustained nasalization of [m] will be more in correspondence with the humming sound of the bumble bee. The clinical importance of humming sound has been investigated in many recent research reports. In [18],[19] it has been shown that humming through nasal airways improves Nitric Oxide (NO) ventilation which is good for clearing and maintaining good health of sinus. However, these experiments were not with BP but are related with the humming sound similar to that produced during BP. In the many previous studies, it has been reported that the paranasal sinuses are filled with NO which maintains sterility of the sinus cavity due to its antiviral and bacteriotoxic properties. Thus exchange of NO Fig.6 Nitric Oxide (NO) output in exhalation with with sinus cavity is essential for the healthy condition of sinus. humming (shown by dotted line) and without humming Often surgical treatment of blocked sinus is done to improve (shown by solid line) (With courtesytaken from reference such ventilations. Fig.6 shows amount of nitric oxide output in [20]. one exhalation with and without humming. A single exhalation with humming takes out more than 86% of the total sinus

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III. ANALYSIS OF HUMMING SOUND OF BP We assume that the humming sound is playing key role in bringing positive effects. In order to make preliminary studies on the humming sound produced during BP, we have collected humming sound from three regular practitioners (two male and a female) of BP by placing microphones near nostrils. The subjects made humming sound by the sustained pronunciation of [m] sound (as the last part of OM) sound. The sampling frequency was kept at 8000 Hz. The waveform of humming (d) sound from male subject is shown in Fig. 7. The [O] part and sustained [M] part of the waveforms were separated manually and for a subject these are shown in Fig.8 (a) and (b). The pitch of the sound is plotted in the Fig.8(c). The pitch was extracted using autocorrelation based algorithm. The pitch during humming part (mm…sound) shows very little variation. The pitch graph in the case of female subject has been found with the similar trends with pitch at higher value, which is natural.

The power spectrum and spectrogram of the sound are also shown in Fig 8(d) and (e) from where it can be imbued that (e) energy is concentrated in lower frequency bands similar to that Fig.8 (a) 'O' part of the humming (b)'MM…'.part of the of bumble bee. The concentration of energy in lower frequency humming (c)Pitch of the humming sound of Fig.7. (d) components can be useful in making better ventilation of NO Power spectral Density (PSD) of humming sound of shown from sinus cavities which explains usefulness of BP for it. in Fig.7 and (e) Spectrogram of the humming sound.

Fig. 9. PSD of humming sound during BP with closed ear Fig. 7 Humming sound produced by sustaining [m] part and opened ear. of the OM.

As mentioned earlier that during BP subject has to close ears by finger. The PSD of humming with and without closing ears are almost same. This has been shown in the Fig.9. However, subjective feeling of each subject is that internal audition is suppressed by external audition with open ears. The closure of ear makes bone conducted sound dominating in audition and vibrational effect of humming is felt strongly. It is argued that when ears are closed the sound pressure level of bone (b)'MM…'.part. (a) 'O' part. conducted sound increases in the inner ear which might be giving stronger vibration and in the open ear condition the bone conducted sound is getting out through ear weakening vibration. However, this is a matter of experimental verification which has not been done in the present studies.

IV. GENERAL DISCUSSION AND RESEARCH ISSUES This is precursor paper with preliminary results on the yogic act

BP in which human is imitating sound of an insect. It is (c) effective in abolishing many mental problems of everyday life. Our final aim is to develop an acoustic system for the challenged people to provide mental tonic in form of sound imitating BP. At present, we do not have much explanation for

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the effect of BP. There are many things involved in BP such as with different phenomena of our mind and body ranges from the role of eye closure, body posture etc. which are unexplored. very low to very high [28]. The interaction and transmission of Here we have taken one of the very active sub-processes of BP acoustic vibrations to other part of bodies during BP cannot which is humming like bumble bee and have tried to find also be denied. However, such assumptions are subject to similarities with the humming sound of the bumble bee. experimental verifications. However, even with found similarities we cannot explain how humming is working in bringing soothing effects? Unless V. CONCLUSIONS AND FUTURE WORK transmission of sound starting from vocal fold and nasal cavity The preliminary results on the humming sound produced into head is not explored, nothing concrete can be said. The during BP and that of bumble bee shows correspondence in effect of vibration produced by humming sound on the brain is spectral contents, which has been established in this paper. We also not known and researches in this direction will help in are interested in discovering the internal mechanism of BP that explaining mechanism behind which brings effect of BP. In the brings positive effects on mind and body and design a light of postulates made in [24], it seems convincing that biomimetic system that can give benefits of BP to challenged humming sound of BP produces massaging effect on Brain and people like dumb. Next we are doing Electroencephalographic accelerates process of diffusion by which waste products from (EEG) recording experiments to quantify effect of BP on brain are removed. Brain is forted by Blood Brain Barrier brainwave patterns. 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