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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 23  |  Issue : 4  |  Page : 230-232

Effect of practicing yoga on functioning of efferent auditory system


Department of Audiology, All India Institute of Speech and Hearing, Mysore, Karnataka, India

Date of Web Publication2-May-2018

Correspondence Address:
Dr. Prashanth Prabhu
Department of Audiology, All India Institute of Speech and Hearing, Manasagangothri, Naimisham Campus, Mysore - 570 006, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/indianjotol.INDIANJOTOL_87_17

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  Abstract 


Introduction: The present study attempted to determine the effect of practicing Yoga on the functioning of the efferent auditory system using contralateral suppression of otoacoustic emissions (OAE). Method: The efferent suppression of transient evoked OAE (TEOAE), and distortion product OAE (DPOAE) was recorded from 40 participants (20 who practice Yoga regularly and 20 who do not practice yoga regularly). Results: The results of this study showed that there was an increase in the amount of suppression of both TEOAE and DPOAE in individuals who practice Yoga. The result suggests that Yoga enhances the sensory perception and improves auditory attention. The constant practice of Yoga could have led to the plasticity of the efferent auditory system. Conclusions: Thus, the practice of Yoga may be used to strengthen the efferent auditory system. However, further studies on a larger group of the population are essential for better clinical applicability of the results.

Keywords: Contralateral suppression, efferent auditory system, otoacoustic emissions, yoga


How to cite this article:
Kumar SD, Shambhu T, Prabhu P. Effect of practicing yoga on functioning of efferent auditory system. Indian J Otol 2017;23:230-2

How to cite this URL:
Kumar SD, Shambhu T, Prabhu P. Effect of practicing yoga on functioning of efferent auditory system. Indian J Otol [serial online] 2017 [cited 2018 Aug 15];23:230-2. Available from: http://www.indianjotol.org/text.asp?2017/23/4/230/231651




  Introduction Top


The outer hair cells of the organ of Corti are the target of abundant efferent projections from the olivocochlear system. The efferent auditory system plays an important role in human auditory perception. The medial olivocochlear (MOC) bundle plays a major role in auditory attention.[1],[2],[3] The efferent system causes inhibition of responses which are not important and thus enhances attention.[4] A study done by Froehlich et al.[5] showed a decrease in amplitude of transient evoked otoacoustic emissions (TEOAE) with selective attention to auditory and visual stimulus thus evidencing the fact that MOC plays a role in attention and it can be assessed using contralateral suppression of otoacoustic emissions (OAE). The medial efferent system functioning is generally assessed using contralateral suppression of OAE [6] which is reported to be modulated by auditory attention.[1],[7] In general, it involves the recording of OAE in the absence and in the presence of acoustic stimulation which is usually a broadband noise (BBN). This BBN, in turn, activates the contralateral MOC reflex, thereby leading to decrease in OAE amplitude. Yoga is an ancient technique used effectively to improve concentration and enhance attention.[8] Practicing yoga regularly is in turn found to improve attention and memory.[9]

Yoga incorporates different physical postures, breath control, mental concentration, and deep relaxation to positively affect the mental states of the body.[10] Yoga also promotes self-control, attention and concentration, self-efficacy, body awareness, and stress reduction.[11] Hence, the improved attention because of practicing Yoga may induce plasticity in the neural system important for attention. It is also well reported that efferent auditory system plays a vital role in improving auditory attention.[1],[2] Research also shows that there is enhanced activity of the MOC system in musicians when compared to nonmusicians because of higher auditory attention.[12],[13],[14] Walsh et al.,[15] in their study reported that auditory efferent system was more active during selective attention for both visual and auditory tasks. Thus, there are evidence to show that yoga enhances attention [8] and auditory attention modulates olivocochlear efferent functioning.[1],[3] However, there is a paucity of literature in the objective estimation of auditory attention in healthy individuals who practice yoga regularly. Thus, the present study attempts to investigate if there in any difference in olivocochlear activity between individuals who practice and do not practice Yoga regularly. The difference in the amount of suppression of transient evoked OAE (TEOAE), and distortion product OAE (DPOAE) between the two groups was determined.


  Materials and Methods Top


Participants

A total of 40 normal hearing individuals in the age range of 20–40 years participated in the present study. They were further divided into two groups based on who practice Yoga (20 participants– Experimental group; 6 females and 14 males) with an average age of 34 years and those who do not practice Yoga (20 participants– Control group; 8 females and 12 males) with an average age of 31 years. The results of Mann–Whitney U-test suggested that there was no significant difference in age and gender (P > 0.05) between both the groups considered for the study.

Participant selection criteria

Participants of both the groups had hearing sensitivity within normal limits. The participants did not have a history of any otologic symptoms, use of ototoxic drugs, metabolic and systemic disease causing hearing loss, history of neurological factors or psychological problems and no history of smoking and consumption of alcohol. They also had no history of cardiovascular problems. The participants in both the groups were not under any pharmacological treatment. The duration of Yoga practice in the clinical group ranged from at least 5 years to 10 years (Mean = 7.2 years).

Procedure

All participants were subjected for pure tone audiometry for air conduction and bone conduction testing across frequencies 250, 500, 1000, 2000, 4000, and 8000 Hz using a calibrated inventis piano audiometer in an acoustically treated booth. Tele Dynamic Headphone-39 headphones were used for air conduction testing, and the B-71 bone vibrator was used for bone conduction testing. The thresholds were measured using a modified version of Hughson–Westlake procedure.[16] A calibrated Grason Stadler, Inc. TympStar middle-ear analyzer was used for tympanometry and reflexometry. Probe tone frequency of 226 Hz was used to carry out immittance evaluation. Tympanogram was obtained by changing the pressure within the ear canal from +200 to −400 daPa. Ipsilateral and contralateral acoustic reflexes thresholds were measured for 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz.

All OAE measurements were performed for the right ear and recorded using the ILO V6 OAE equipment in a sound-treated room. The only right ear was tested as OAE suppression is reported to be more in the right ear.[17] TEOAE amplitude (dB SPL) for the frequency bands centered at 1000, 1500, 2000, 3000, and 4000 Hz was recorded using nonlinear click trains of stimuli with the level of 80 dB peak SPL ensuring appropriate probe fit. Second TEOAE amplitude (dB SPL) for the frequency bands centered at 1000, 1500, 2000, 3000, and 4000 Hz was recorded by presenting a contralateral BBN through audiometer at 40 dB SPL. Similarly, distortion product signal amplitude across the frequencies of 1000 Hz, 2000 Hz, 3000 Hz, 4000 Hz, 5000 Hz, 6000 Hz, and 8000 Hz was recorded with and without contralateral white noise at 40 dB SPL.

Ethical considerations

In the present study, all the testing procedures done were using noninvasive technique adhering to conditions of ethical approval committee of the institute. All the test procedures were explained to the patients before testing, and informed consent was obtained from all the patients for participating in the study.


  Results Top


The results of the present study showed that there was an increase in the amount of suppression for individuals who practice Yoga (experimental group) compared to those who do not practice Yoga (control group). The mean and standard deviation of the amount of suppression for TEOAE and DPOAE across both groups are shown in [Figure 1] and [Figure 2], respectively.
Figure 1: Mean and standard deviation of the amount of transient evoked otoacoustic emissions suppression across both groups

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Figure 2: Mean and standard deviation of the amount of distortion product otoacoustic emissions suppression across both groups

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The Shapiro–Wilks test of normality showed that the data were not normally distributed, thus nonparametric inferential statistics were done. Mann–Whitney U-tests were done to compare the difference in the amount of suppression across two groups for TEOAE and DPOAE. Results of Mann–Whitney U-test showed that there was a significant increase (P < 0.05) in the amount of suppression in the experimental group compared to control group for both TEOAE and DPOAE. The amount of suppression was averaged across all frequencies for each participant, and the mean differences were also analyzed. The result of Mann–Whitney U-tests showed that there was a significant increase (P < 0.05) in the amount of suppression (~2 dB for TEOAE and ~ 3 dB for DPOAE) in individuals who practice Yoga.


  Discussion Top


The results of this study showed that there is an increase in the amount of contralateral suppression of OAE in individuals who practice Yoga. This increased suppression suggests the higher activity of efferent auditory system in people who practice Yoga. It is well reported that MOC bundle plays an important role in auditory attention.[1],[2],[3] The results of the study showed that there was increased activation of medial olivocochlear bundle functioning in individuals who practice Yoga. The increased contralateral suppression of OAE suggests that there is an enhancement of auditory attention in individuals who practice Yoga. Yoga is reported to improve mental concentration and enhancement of sensory and perceptual skills.[10] Yoga is also reported to improve the processing speed, working memory, concentration, and overall cognitive functioning.[9],[11]

There is extensive evidence which suggests that efferent auditory system is strengthened with training.[12],[13],[14] It is reported that the medial olivocochlear system functioning is enhanced in musicians compared to nonmusicians because of higher auditory attention.[12],[13],[14] Walsh et al.,[15] also reported that efferent auditory system was more active during selective attention for both visual and auditory tasks. Yoga has also been used as a therapeutic tool to improve attention in children with attention deficit hyperactivity disorder [8] and other neurological disorders.[18] The result of the present study provides objective evidence of enhanced auditory attention in individuals who practice Yoga. Thus, the study indicates increased plasticity of the efferent auditory system with regular practice of Yoga. Hence, the study highlights the use of Yoga as a tool to improve auditory attention. However, further studies using other sensory modalities on a larger group of individuals are necessary for better generalization of the results.


  Conclusions Top


The present study attempted to determine the effect of practicing Yoga on the functioning of the efferent auditory system using contralateral suppression of OAE. The results of this study showed that there was an increase in the amount of suppression of OAE in individuals who practice Yoga. It suggests that Yoga enhances the sensory perception and improves auditory attention. The constant practice of Yoga could have led to the plasticity of the efferent auditory system. Thus, the practice of Yoga may be used to strengthen the efferent auditory system. However, further studies on a larger group of the population are essential for better clinical applicability of the results.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Giard MH, Collet L, Bouchet P, Pernier J. Auditory selective attention in the human cochlea. Brain Res 1994;633:353-6.  Back to cited text no. 1
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de Boer J, Thornton AR. Neural correlates of perceptual learning in the auditory brainstem: Efferent activity predicts and reflects improvement at a speech-in-noise discrimination task. J Neurosci 2008;28:4929-37.  Back to cited text no. 2
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Hill JC, Prasher DK, Luxon LM. Latency of contralateral sound-evoked auditory efferent suppression of otoacoustic emissions. Acta Otolaryngol 1997;117:343-51.  Back to cited text no. 3
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Scharf B, Magnan J, Collet L, Ulmer E, Chays A. On the role of the olivocochlear bundle in hearing: A case study. Hear Res 1994;75:11-26.  Back to cited text no. 4
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Froehlich P, Collet L, Morgon A. Transiently evoked otoacoustic emission amplitudes change with changes of directed attention. Physiol Behav 1993;53:679-82.  Back to cited text no. 5
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Peck HL, Kehle TJ, Bray MA, Theodore LA. Yoga as an Intervention for children with attention problems. School Psych Rev 2005;34:415-24.   Back to cited text no. 8
    
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Micheyl C, Khalfa S, Perrot X, Collet L. Difference in cochlear efferent activity between musicians and non-musicians. Neuroreport 1997;8:1047-50.  Back to cited text no. 13
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Perrot X, Micheyl C, Khalfa S, Collet L. Stronger bilateral efferent influences on cochlear biomechanical activity in musicians than in non-musicians. Neurosci Lett 1999;262:167-70.  Back to cited text no. 14
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Walsh KP, Pasanen EG, McFadden D. Changes in otoacoustic emissions during selective auditory and visual attention. J Acoust Soc Am 2015;137:2737-57.  Back to cited text no. 15
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Khalfa S, Veuillet E, Collet L. Influence of handedness on peripheral auditory asymmetry. Eur J Neurosci 1998;10:2731-7.  Back to cited text no. 17
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Balasubramaniam M, Telles S, Doraiswamy PM. Yoga on our minds: A systematic review of yoga for neuropsychiatric disorders. Front Psychiatry 2012;3:117.  Back to cited text no. 18
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    Figures

  [Figure 1], [Figure 2]



 

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