ArticlePDF Available

Effects of binaural beats and isochronic tones on brain wave modulation: Literature review

Authors:

Abstract and Figures

This systematic review is dedicated to deepening the study of two phenomena: binaural beats and isochronic tones. Data from the scientific literature suggest the existence of a promising therapeutic potential in neurology and psychophysiology due to their influence on specific frequencies of brain waves and their implications for mental health and homeostasis of brain neurotransmitters. Prolonged audio stimuli in repetitive and synchronized manner may induce changes in brain waves patterns and, consequently, modulating neurophysiological, and behavioral responses. The literature review was conducted using PUBMED, MEDLINE, LILLACS, and SCIENCE DIRECT online platforms using the search words: “audio brain entrainment,” “auditory beat stimulation, “ “binaural beats,” “brainwave entrainment (BWE),” and “isochronic tones.” The search yielded 674 studies, of which 49 were in duplicate, and 592 were out of the scope of this review, and, therefore, were excluded from the study. The remaining studies were analyzed according to the Cochrane Handbook for Systematic Reviews, resulting in 33 randomized, controlled clinical trials that were then evaluated by the Jadad scale. From that, 17 studies obtained a score of three points or more on the Jadad scale. These studies were fully read and critically analyzed. Binaural beats were used in 15 studies (88.25%), whereas isochronic tones were used only in two studies (11.76%). Although most of the studies reviewed here indicated audio BWE effectiveness, some positive outcomes may require further investigation, with more refined and appropriate evaluation tools, better suited for each specific type of intervention and/or therapeutic target. Considering these limitations, the performance of additional studies with more adequate experimental design and data analysis is recommended, particularly focusing on the neurophysiological and behavioral effects of brain wave entrainment on mental states.
Content may be subject to copyright.
238
Effects of binaural beats and isochronic tones on brain wave
modulation: Literature review
Sandro Aparecido-Kanzler1*, Francisco J. Cidral-Filho2, and Rui D. Prediger1,3
1Department of Neuroscience, Center of Biological Sciences, Federal University of Santa Catarina (UFSC), Florianopolis; 2Experimental Neuroscience
Laboratory (LaNEx), University of Southern Santa Catarina (UNISUL), Palhoça, Santa Catarina; 3Department of Pharmacology, Center of Biological
Sciences, Federal University of Santa Catarina (UFSC), Florianopolis. Brazil
Revista Mexicana de Neurociencia
REVIEW ARTICLE
Abstract
This systematic review is dedicated to deepening the study of two phenomena: binaural beats and isochronic tones. Data
from the scientific literature suggest the existence of a promising therapeutic potential in neurology and psychophysiology
due to their influence on specific frequencies of brain waves and their implications for mental health and homeostasis of
brain neurotransmitters. Prolonged audio stimuli in repetitive and synchronized manner may induce changes in brain waves
patterns and, consequently, modulating neurophysiological, and behavioral responses. The literature review was conducted
using PUBMED, MEDLINE, LILLACS, and SCIENCE DIRECT online platforms using the search words: “audio brain entrain-
ment, “auditory beat stimulation, “binaural beats, “brainwave entrainment (BWE), and “isochronic tones. The search yielded
674 studies, of which 49 were in duplicate, and 592 were out of the scope of this review, and, therefore, were excluded from
the study. The remaining studies were analyzed according to the Cochrane Handbook for Systematic Reviews, resulting in
33 randomized, controlled clinical trials that were then evaluated by the Jadad scale. From that, 17 studies obtained a score
of three points or more on the Jadad scale. These studies were fully read and critically analyzed. Binaural beats were used
in 15 studies (88.25%), whereas isochronic tones were used only in two studies (11.76%). Although most of the studies re-
viewed here indicated audio BWE effectiveness, some positive outcomes may require further investigation, with more refined
and appropriate evaluation tools, better suited for each specific type of intervention and/or therapeutic target. Considering
these limitations, the performance of additional studies with more adequate experimental design and data analysis is recom-
mended, particularly focusing on the neurophysiological and behavioral effects of brain wave entrainment on mental states.
Key words: Audio brain entrainment. Binaural beats. Brainwave entrainment. Isochronic tones.
Efectos de los tonos binaurales y isocrónicos en la modulación cerebral: Revisión de
la literatura
Resumen
Esta revisión sistemática está dedicada a profundizar en el estudio de dos fenómenos: latidos binaurales y tonos isocróni-
cos. Los datos de la literatura científica sugieren la existencia de un potencial terapéutico prometedor en neurología y psi-
cofisiología debido a su influencia en frecuencias específicas de ondas cerebrales y sus implicaciones para la salud
mental y la homeostasis de los neurotransmisores cerebrales; los estímulos de audio repetitivos y sincronizados pueden
inducir cambios en los patrones de ondas cerebrales y modular las respuestas neurofisiológicas. La revisión de la literatura
Correspondence:
*Sandro Aparecido-Kanzler
E-mail:kanzlersa@gmail.com
Available online: 15-11-2021
Rev Mex Neuroci. 2021;22(6):238-247
www.revmexneurociencia.com
Date of reception: 15-09-2020
Date of acceptance: 17-05-2021
DOI: 10.24875/RMN.20000100
2604-6180/ © 2021 Academia Mexicana de Neurología A.C. Published by Permanyer. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
No part of this publication may be reproduced or photocopying without the prior written permission of the publisher. © Permanyer 2021
239
S. Aparecido-Kanzler, et al.: Binaural and isochronic tones in brain
Introduction
Brain waves consist of rhythmic patterns of neuronal
activity or synchronized electrochemical pulses from
groups of neurons in the central nervous system (CNS)1.
There are several well-established brainwave range
patterns: gamma (30-70Hz), beta (13-30Hz), alpha (8-
13Hz), theta (4-8Hz), and delta (1-4Hz)2. Each one of
these frequency bands has been correlated with differ-
ent states of consciousness, such as awake, relaxed,
rapid eye movement (REM) sleep, as well as non-REM
sleep stages3.
According to Gruzelier4, prolonged audio stimuli in
repetitive and synchronized manner may induce chang-
es in brain waves patterns and, consequently, may
modulate neurophysiological and behavioral respons-
es. More specifically, repetitive external or environmen-
tal stimuli may temporarily affect the predominance of
specific brain wave frequencies, a phenomenon namely
brainwave entrainment (BWE)5-7. Therefore, BWE can
be defined as rhythmic synchronization of brainwave
oscillation with an external repetitive stimulus.
BWE is a recurrent phenomenon in nature and bio-
logically present in living beings8. The principle of en-
trainment or harmonization was discovered around
1665, by the Dutch scientist Christian Huygens9. The
synchronization obtained through the entrainment prin-
ciple is the result of the harmonization principle, a phys-
ical phenomenon that occurs systematically in nature,
and that is dependent on environmental stimuli, for
example, visual, auditory, or tactile. These stimuli may
be used to elicit synchronized brainwave patterns to
match that of different mental states and/or levels of
consciousness, as seen with data acquisition tech-
niques, such as the electroencephalography (EEG). In
this context, Oster10 stated the possibility to improve,
amplify or modulate brain wave patterns to conditioned
events in the cerebral cortex3,11. The proposed thera-
peutic benefits have a wide scope, including the im-
provement of cerebral blood flow, neuroplasticity
stimulation, and neurophysiological compensations be-
tween the cerebral hemispheres3.
In this review, we focused on the most common forms
of auditory BWE, that is, binaural beats and isochronic
tones. Acoustic waves are characterized in Hertz (num-
ber of cycles per second). The audible sound spectrum
for humans comprises frequencies between 20Hz and
20,000Hz, regardless of its complexity, and as long as
it has an amplitude greater than 0dB (decibel)12,13.
Isochronic tones consist of distinct and repetitive reg-
ular beats of a single tone. The number of peaks per
second in the signal amplitude is the isochronic fre-
quency heard at regular and standardized time inter-
vals. On the other hand, binaural beats represent the
auditory experience that occurs when two sounds of
close frequencies are presented separately to each ear
with headphones or stereo speakers. The brain inte-
grates the two signals, producing a third “phantom
sound” representing the difference between the two
auditory stimuli. For example, if a frequency of 114 Hz
is presented to the right ear, and another of 124Hz to
left ear, a binaural beat of 10Hz is created by the brain
as a result of these stimuli. In this case, brain waves
tend to match the binaural beat frequency, in this ex-
ample 10 Hz, which corresponds to alpha brainwave
pattern. Binaural beats are created in the superior oli-
vary nucleus of the brain stem, the local of contralateral
integration of auditory input14 (Fig.1).
The beat is neurologically transported to the reticular
formation, which uses neurotransmitters to trigger
changes in brain wave activity10 that synchronizes with
that of the stimulus generated. The mental features
se realizó con plataformas en línea PUBMED, MEDLINE, LILLACS y SCIENCE DIRECT, con las palabras de búsqueda: “ar-
rastre cerebral de audio”, “estimulación del ritmo auditivo”, “ritmos binaurales”, “arrastre de ondas cerebrales” y “tonos isocróni-
cos”. La búsqueda produjo 674 estudios, de los cuales 49 estaban duplicados y 592 estaban fuera del alcance de esta
revisión y fueron excluidos. Los estudios restantes se analizaron de acuerdo con el Manual Cochrane de Revisiones
Sistemáticas, que tuvo como resultado 33 ensayos clínicos controlados aleatorios que fueron evaluados por la escala de
Jadad. Apartir de esto, 17 estudios obtuvieron una puntuación igual o superior a tres puntos y fueron leídos íntegramente
y analizados críticamente. Los tonos binaurales se utilizaron en 15 estudios (88. 25%) y los tonos isocrónicos sólo en 2
estudios (11. 76%). Aunque la mayoría de los estudios revisados demuestran la eficacia del arrastre de ondas cerebrales,
algunos resultados pueden requerir más investigación con herramientas más refinadas y apropiadas, para cada intervención
y/u objetivo terapéutico. Teniendo en cuenta estas limitaciones, se recomienda que se lleve a cabo un diseño experimental
y análisis de datos más adecuados, centrándose en los efectos neurofisiológicos del arrastre de ondas cerebrales y los
estados mentales.
Palabras clave: Estimulación cerebral con audio. Tonos binaurales. Arrastre de ondas cerebrales. Tonos isocrónicos.
No part of this publication may be reproduced or photocopying without the prior written permission of the publisher. © Permanyer 2021
240
Rev Mex Neuroci. 2021;22(6)
associated with each brain wave pattern can be elicited
based on the scientific principle of harmonization, also
known as “brain wave entrainment.”
Most of studies with binaural beats and isochronic
tones provides positive outcomes, indicating that audio
brain entrainment may yield different benefits, both
physically and mentally15,16. More specifically, brain en-
trainment can be applied to induce mental states and
as adjunctive treatment to several brain disorders in a
safe and non-invasive manner, such as for the treat-
ment of depression and anxiety disorders17. For in-
stance, it was demonstrated that a group of individuals
exposed to 6Hz sounds for 10min presented a signif-
icant increase on theta wave (4-8 Hz) cortical activity
in comparison to control group that did not receive the
stimulus. These findings indicate a facilitatory effect on
induction of a meditative state and altered states of
consciousness18. In this context, the aim of this study
was to review the scientific evidence on the therapeutic
use of binaural beats and isochronic tones for the mod-
ulation of brain wave patterns and mood states.
Development
Methodology
The central question of the current study was: what
are the therapeutic and/or neuroplastic and behavioral
effects of binaural beats and isochronic tones on brain
wave patterns and mood state modulation?
The following electronic databases were used for the
studies search: PUBMED, MEDLINE, LILLACS, and
SCIENCE DIRECT, and the following search words (key
words) were used: “audio brain entrainment,” “auditory
beat stimulation,” “binaural beats,” “BWE,” and “iso-
chronic tones.”
The bibliographic search was conducted inde-
pendently by the authors from October to December
2019, and blindly to the results obtained by the other
authors. The studies that met inclusion criteria (see
below) were later compared and compiled. The Co-
chrane Handbook for Systematic Reviews19 recommen-
dations were followed to assess the risk of bias; and
the Jadad scale20 to evaluate methodological quality.
The Jadad scale consists of five criteria items, ranging
from 0 to 5 points. A score below 3 indicates low
methodological quality and a score of 3 points or
more indicates superior methodological quality.
The scale consists of the following questions:
1. Was the study randomized?
2. Was the randomization method appropriate?
3. Was the study blinded? Double blinded?
4. Was the blinding method appropriate?
5. Were drop-offs properly reported?
For questions 1, 3, and 5, a single point for yes, or zero
for no, is assigned. For questions 2 and 4, a single point
for the use of the appropriate method, zero points for no
Figure1. Binaural beats generated by the brain.
No part of this publication may be reproduced or photocopying without the prior written permission of the publisher. © Permanyer 2021
241
S. Aparecido-Kanzler, et al.: Binaural and isochronic tones in brain
description of the method, or a single negative point for
the inappropriate use of the method is assigned.
Inclusion criteria
The following criteria were included in the study:
1. Publication date: studies published from 2009 to 2019
2. Study design: clinical studies, such as case report,
case series, case-control study, non-randomized
controlled clinical trial, and randomized clinical trial
3. Population: without limitation
4. Intervention: stimulation with binaural beats or iso-
chronic tones
5. Comparison: without limitation
6. Result: qualitative and quantitative.
Results
The search yielded a total of 674 studies (PUBMED:
74; MEDLINE: 396; LILLACS: 138; and SCIENCE DI-
RECT: 66). As illustrated in figure 2, from the total of
studies, 49 studies were in duplicate, and 592 studies
addressed other themes beyond the scope of this re-
view, and, therefore, were excluded from the study.
The selected studies were analyzed according to the
Cochrane Handbook for Systematic Reviews19, result-
ing in 33 randomized, controlled clinical trials that were
then evaluated by the Jadad scale20 (Fig. 3). Only 17
studies obtained a score of three points or more on the
Jadad scale20, and them were fully read and critically
analyzed; studies are summarized in Table 1. Binaural
beats were used in 15 studies (88.25%) whereas iso-
chronic tones were used in only two studies (11.76%)
(Fig.3). In 82.35% of these publications monaural and/
or binaural audio stimulation were more effective in
comparison to control group.
After the evaluation made by the Jadad scale, the 17
selected studies were classified according to the meth-
odological criteria adopted in each experiment (Ran-
domized Study (R); Double Blind Study (BD), Controlled
Study with Placebo (PC), type of sample and number
of individuals in the study and results obtained by each
researcher. The summary of therapeutic targets and
forms of intervention and approaches of these selected
studies are described in Ta b le 2.
Main ndings of the studies addressing
the effects of brain waves on mental states
In this section is presented a description of the dif-
ferent brainwaves, their effects, and the discussion of
the main findings obtained in the studies reviewed
here. The study performed by Washington and collab-
orators21 indicated that each brain wave frequency pro-
duces particular neurophysiological and cognitive
effects, been associated with a specific state of
consciousness.
Delta waves (< 4 Hertz): the slowest waves are as-
sociated with the deepest state of sleep and uncon-
scious. These waves represent the ideal for sleep,
physical and mental recovery, and deep meditation.
Delta waves lead to a state of mental happiness and
empathy where the person feels more connected with
her/himself. This state improves intuition and memory.
Delta waves are associated with the release of growth
hormone22, which is beneficial for cell regeneration, as
well as the production of endogenous opioids23. None
of the selected studies review here used delta waves.
Theta waves (4-8Hz): this frequency pattern is relat-
ed to the processes of creativity, enhanced intuition,
more intense emotional connections that elevate sen-
sitivity, and a sense of tranquility and reduced anxiety.
Theta waves also contribute to the improvement of
problem-solving skills and retention of much larger
amounts of information in shorter period of time. This
pattern is associated with decreased levels of serum
cortisol and with the modulation of serotonin and mel-
atonin. Theta waves generate a relaxed state of
consciousness24,25.
Eight of the studies reviewed here were conducted
with Theta waves, with binaural beats as well as iso-
chronic tones interventions. Major targets were cogni-
tive and/or pathological states. Increased long-term
memory performance was observed in patients with
epilepsy who underwent 6-min 5Hz brain entrainment
sessions, once a week for 6 weeks with binaural and
isochronic tones26. On the other hand, in non-epileptic
adult subjects, 15-min 5Hz brain entrainment sessions
did not induce significant effects27. Visuospatial working
memory and cortical connectivity were not altered fol-
lowing a single intervention of 5 min with 5Hz thera-
py28. Another study using binaural beats also describes
absence of significant effects in the working memory
of healthy young adults29. Interestingly, 20-min 6 Hz
binaural beat entrainment twice a week for 14 days
effectively reduced the perception of pain severity16.
In addition, in patients with temporal lobe epilepsy who
underwent brain implants with EEG signal control, acute
therapy of temporolateral (5 Hz for 5 min) increased
memory acuity with EEG synchronization17. Moreover, in
young adult’s post-physical training, binaural beat en-
trainment (4-7Hz for 20min) increased parasympathetic
No part of this publication may be reproduced or photocopying without the prior written permission of the publisher. © Permanyer 2021
242
Rev Mex Neuroci. 2021;22(6)
activation and self-reported relaxation30. Finally, a single
intervention with isochronic tones at 6, 10 and 40 Hz
during 5 min reduced anxiety and improved well-being
reports of healthy individuals31.
Alpha waves (8-13Hz): this frequency pattern is re-
lated to mental relaxation32, visualization, and creative
processes; therapeutically uses include memory opti-
mization, and modulation of pain perception threshold.
The use of this wave pattern in the elderly population
has been shown an excellent therapeutic potential to
treat memory disorders33.
Alpha waves were used with a therapeutic and/or
neurocognitive focus in six studies reviewed here.
Vernon et al.34 reported that 10Hz alpha pattern for 1
or 5min did not elicit significant EEG alteration. How-
ever, isochronic stimulation with 7 Hz for 9 min with
3min intervals induced temporal and parietal lobe ac-
tivation with the potential to alter brain networks in
adult’s healthy young individuals35. Alpha binaural
beats for 3min in healthy young adults did not affect
attentional blink (AB) control with the EBR method (pre-
dictor of mood states associated with dopamine lev-
els)36. Moreover, patients with temporal lobe epilepsy
who underwent brain implants, the acute exposure to
10Hz isochronic tones for 5min increased significantly
medio temporal synchronization17,30.
Figure2. Randomization algorithm and study selection.
Figure3. Summary of the selected studies - handbook for systematic reviews.
No part of this publication may be reproduced or photocopying without the prior written permission of the publisher. © Permanyer 2021
243
S. Aparecido-Kanzler, et al.: Binaural and isochronic tones in brain
Study Method and Sample
size (N)
Population/Type/Special? Number of interventions and
frequency
Outcomes
Kennel et al.,
201044
R+DB+PC; 20. Male and female children
and adolescents with
Attention-deficit/
hyperactivity disorder
3 weeks with three interventions
per week with binaural beta-16
Hz- beats 10 min
Improved focus and
attention
Vernon et al.,
201434
R, 22 Healthy male and female
young adults
Acute intervention (single):
10 Hz (Alpha)
20 Hz (Beta)
Induced brainwave
entrainment
McConnell et al.,
201430
R+DB+PC, 21 Young adults post-
exercise
Single post-workout
intervention of 4-7 Hz theta
waves
Increased
parasympathetic
activation, increased
sympathetic withdrawal,
and increased
self-reported relaxation
after exercise
Becher et al.,
201517
R+PC, 10 Patients with temporal
lobe epilepsy
Acute pre-surgical intervention,
the duration of the main
experiment varied between 15
and 40 min, and the total
number of auditory stimuli
varied between 87 and 214 Hz
Increased intracranial
flow modulation in
patients with temporal
lobe epilepsy
Reedjik et al.,
201536
R+PC, 24. Healthy male and female
young adults
Applications of binaural
frequencies of gamma
frequency (40 Hz) and alpha
(10Hz), for 3 min before and
during a global-local task
Measurement and
control of attentional
blink (AB), EBR method
(predictor of dopamine
levels and mood states)
Tirdad et al.,
201535
R+PC, 15 Healthy male and female
young adults
Intermittent intervention of
3 min with 1 min of intertrial
interval, 7 Hz applications of
binaural tones during 9 min
Promoted brainwave
entrainment
Colzato et al.,
201654
R+PC+DB, 40 Healthy male and female
adults
Single 40 Hz gamma binaural
beat intervention
Improved selective
attention
Zampi,
201616
R+PC, 36 Chronic pain patients Sequential intervention for
14days with Theta 6 Hz
Attenuated severity of
pain
Beaucheneet al.,
201628
R+PC, 28 Healthy male and female
young adults
Acute intervention (single) with
six acoustic stimulation
conditions: None, Pure Tone,
Classical Music, 5 Hz, 10 Hz
and 15 Hz binaural beats
Improved visuospatial
working memory
performance and
cortical connectivity
Beauchene et al.,
201729
R+PC, 34 Healthy male and female
young adults
Acute intervention (single) with
six acoustic stimulation
conditions: None, Pure Tone,
Classical Music, 5 Hz, 10 Hz
and 15 Hz binaural beats
Improved working
memory performance
Colzato et al.,
201753
R+PC+DB, 36 Healthy male and female
young adults
Acute intervention (single)
applications of binaural
frequencies of gamma frequency
(40 Hz), for 3 min before and
during a global-local task
High frequency binaural
beats improved the
attention
Lopez-Caballero
and Escera,
201758
R+PC, 40. Healthy male and female
young adults
Beats of 5 different frequencies
(4.53 Hz - theta -, 8.97 Hz
-alpha-, 17.93 Hz -beta-, 34.49
Hz -gamma -or 57.3 Hz-super-
gamma) binaurally and
acoustically for 3 min, preceded
and followed. For periods of
white noise of 90 s (baseline
and post values, respectively)
Promoted brainwave
entrainment
Table 1. Summary of the main findings of the 17 selected studies according to the therapeutic use of binaural beats
and isochronic tones auditory brainwave entrainment
(Continues)
No part of this publication may be reproduced or photocopying without the prior written permission of the publisher. © Permanyer 2021
244
Rev Mex Neuroci. 2021;22(6)
Beta waves (13-39Hz): this frequency pattern is re-
lated to attention, focus, concentration, and cognition.
Beta BWE was shown to be effective in improving fa-
tigue and some symptoms of attention deficit hyperac-
tive disorder (ADHD), including learning and attention
deficits. Additional studies showed improvement in vi-
sual acuity, coordination, potential for the dyslexia treat-
ment and low of concentration, as well as, to promote
IQ gain in the range of 8-10 points37. Beta wave entrain-
ment influenced self-confidence and socialization and
makes people more optimistic and energetic38-41. Final-
ly, it helps learning as well as sports-related
abilities3,42.
Five independent studies reviewed here used beta
waves. Beauchene et al.28 demonstrated that 15 Hz
beta pattern for 5min increased short-term visuospatial
working memory and cortical connectivity in healthy
young subjects. Asingle 15-min session of 20Hz sig-
nificantly increased long-term memory, improving the
codification of new information without previous mem-
ories24. Interestingly, Vernon et al.34 demonstrated that
two daily sessions (14 Hz, during 10 min) increased
motor and non-motor symptoms in Parkinson’s disease
(PD) patients. In addition, Gálvez et al.43 showed a de-
crease of functional connectivity and optimization of
working memory, with no changes in gait or anxiety
levels in PD patients in comparison to control group.
Kennel et al.44 submitted a group of children and ado-
lescents with diagnosis of ADHD to brain entrainment
sessions (duration of 10 min, 3 days per week for
3weeks). Results were not totally conclusive, although
parents reported improvement in the performance of
homework tasks after the interventions.
Gamma Waves (> 40 Hz): this frequency pattern is
involved in blinking and processing of information from
all parts of the brain. High gamma wave activity in the
brain is associated with intelligence, compassion,
self-control, and feelings of happiness45-48. In addition,
gamma brainwaves have been associated with im-
proved memory and a greater ability of reality percep-
tion49,50. Gamma brainwave activity has been shown to
be increased in monks during meditation51.
Six studies were conducted with gamma BWE. It was
demonstrated that 40Hz gamma stimulation for 20min
improved working memory performance and mnemonic
function in healthy subjects52. AB control, using the
EBR method (predictor of mood states associated with
dopamine levels), was significantly affected by 3-min
binaural gamma stimulation in healthy young adults,
before and during a global-local task36. These benefits
Study Method and Sample
size (N)
Population/Type/Special? Number of interventions and
frequency
Outcomes
Nantawachara
Jirakittayakorn,
201752
R+PC, 40 Healthy male and female
young adults
Applications binaural beats of
gamma frequency (40 Hz), for
20 min before and after
global-local task
Improved working
memory function
assessed by the word
list retrieval task
Chaieb et al.,
201555
R + PC; 15 Epilepsy in pre-surgical
situation
Male and female adults.
6 interventions
1 time per week, 5 Hz theta
binaural tones, 6 min with 3.5 s
and 5 s intervals.
Improved long-term
memory in epileptic
patients
Chaieb et al.,
201731
R+PC; 25 Male and female young
adults
Single progressive intervention
with isochronic tones 6 HZ theta,
10 HZ alpha, and 40 HZ gamma
Reduced anxiety levels
(modulation of mental
states)
Gálvez et al.,
201743
R+DB+PC,14 Parkinson’s disease
patients
2 randomized and
counterbalanced sessions of
sound stimulation (14 Hz
binaural beats) for 10 min
separated by a minimum of 7
days of interval
Improved motor and
non-motor symptoms
including anxiety
symptoms and
cognitive deficits
Garcia-Argibay
etal.,
201727
R+PC, 32 Healthy male and female
adults
Single intervention of 5 Hz theta
waves and another group with
20 Hz Beta
Improved long-term
memory and attention
R: randomized study; DB: double-blinded study; PC: placebo-controlled study.
Table 1. Summary of the main findings of the 17 selected studies according to the therapeutic use of binaural beats
and isochronic tones auditory brainwave entrainment (Continued)
No part of this publication may be reproduced or photocopying without the prior written permission of the publisher. © Permanyer 2021
245
S. Aparecido-Kanzler, et al.: Binaural and isochronic tones in brain
were observed only in individuals with low rates of
spontaneous blinking, which indicates low levels of do-
pamine in the striatum. Colzato et al.53 reported that
3-min 40Hz binaural beats stimulation improved focus
and attention in healthy young adults. Moreover, a
study using 10-min 40Hz stimulation in healthy adults54
demonstrated that BWE acts by modeling specific brain
oscillations, in cognitive processes sustained in the
gamma wave frequency range, such as mental pro-
cesses related to intelligence, self-control, and well-be-
ing. In epileptic patients subjected to brain implants,
acute isochronic tones and binaural beats exposure, in
the range of 40-80Hz for 5min significantly decreased
synchronization in medio-temporal sites, demonstrating
their potential as a non-invasive therapy for modulating
intracranial flow in synchronization of the EEG signals17.
A single intervention with isochronic tones 6, 10, and
40Hz over 5min reduced anxiety and, consequently,
increased the subjects’ well-being, however, without
marked effects on cognition55.
As illustrated in figure 3, in 82.35% of the reviewed
studies, monaural, and/or binaural audio stimulation
were more effective in comparison to control group. As
previously mentioned, binaural beats were used as
therapeutic modality in 15 studies (88.25%), and iso-
chronic tones were only used in two studies (11.76%).
Table 2. Summary of therapeutic applications of different brain waves patterns
Type of intervention Method Time Wave frequency range
Isochronic tones 5,10,40 and 80 Hz Acute
Single sequential
15 to 40 min Theta, alpha, beta, gamma, and super
gamma
Isochronic tones 6,10 and 40 Hz Acute
Single sequential
5 min Alpha, beta, and gamma
Binaural 5,10 and 15 Hz Acute
Single sequential
5 min Theta, alpha and beta
Binaural 40 Hz Acute
Single sequential
20 min Gamma
Binaural 5 and 20 Hz Acute
Single sequential
15 min Theta and beta
Binaural 10 and 20 Hz Acute
Single alternate
1 min Alpha and beta
Binaural 7 Hz Acute
Single
9 min Theta
Binaural 10 and 40 Hz Acute
Single alternate
3 min Alpha and gamma
Binaural 40 Hz Acute
Single
10 min Gamma
Binaural 5,10,40 and 80 Hz Acute
Single sequential
15-40 min Theta, alpha, beta, gamma, and super
gamma
Binaural 4 a 7 Hz Acute
Single sequential
20 min Theta
Binaural 5 Hz Chronic
3 repetitions per week for
6weeks
6 min Theta
Binaural 6 Hz Chronic
2 daily repetitions for 14 days
20 min Theta
Binaural 14 Hz Chronic
2 repetitions a day for 7 days
10 min Beta
Binaural beta - performance range Chronic
3 repetitions per week for
3weeks
10 min Beta
No part of this publication may be reproduced or photocopying without the prior written permission of the publisher. © Permanyer 2021
246
Rev Mex Neuroci. 2021;22(6)
Discussion
The data reviewed in the present study indicates that
binaural beats are more commonly used than isochron-
ic tones, at least in research (as seen in Fig.3). Unfor-
tunately, in our view, there is no standard in the choice
of therapy parameters, such as brainwave range (in
Hz), treatment duration, frequency, and regimen, nei-
ther for the treatment of specific conditions or disor-
ders, nor for simple increase of executive brain functions
and stimulation of inherent mental processes, and neu-
rocognitive performance. Arelevant observation is the
absence of properly controlled double-blinded studies,
which compromises the validity of the results available
in the literature. Nevertheless, the results reviewed
here suggest that auditory BWE, although still scarcely
explored in behavioral and neurophysiological therapy,
may represent an effective and inexpensive therapeutic
approach, with minimal side effects. It is well known
that all brain activity occurs through the bioelectric ac-
tivity of neural networks and that the brain wave phe-
nomenon is produced as a result of the sum of
bioelectric interactions of the billions of neurons and
their trillions of synaptic connections56. Changes in
states of consciousness (concentration, excitement, re-
laxation, sleep, dreams, etc.) are closed related to
changes in the frequency of the vibratory pattern of
brain waves, which varies according to the intensity of
these bioelectric activities.
According to this system and considering that our
state of consciousness is influenced by brain wave
patterns, it is plausible to conclude that BWE can mod-
ulate many aspects of behavior, from states of con-
sciousness to perception, learning, and cognition57.
The adaptation to daily activities requires the brain
ability to modulate brain wave activity, in consonance
to external stimuli and signals, as well as when faced
with challenges and/or problems to be solved. Each
type of brain wave can modulate different neurotrans-
mitter systems, inducing particular synaptic and neuro-
chemical readjustments12,56.
Conclusions
Based on the data reviewed in this study, binaural
beats and isochronic tones BWE may effectively mod-
ulate mood states, improving attention, and memory
processes. Promising results were also obtained in
subjects suffering from different CNS disorders, includ-
ing ADHD, PD, epilepsy, chronic pain, and anxiety
disorders.
Despite the audio BWE effectiveness described in
many studies reviewed here, it is important to empha-
size that some positive outcomes may require further
investigation, with more refined and appropriate evalu-
ation tools, better suited for each specific type of inter-
vention, and/or therapeutic target. Considering these
limitations, the performance of additional studies with
more adequate experimental design and data analysis
is recommended, particularly focusing on the neuro-
physiological and behavioral effects of brain wave en-
trainment on mental states.
Acknowledgments
The authors would like to thank the Experimental
Laboratory of Neurodegenerative Diseases-LEXDON,
Federal University of Santa Catarina – UFSC.
Funding
This research did not receive any specific grants from
agencies in the public, commercial, or non-profit sectors.
Conicts of interest
The authors declare that they have no conflicts of
interest.
Ethical disclosures
Protection of human and animal subjects. The
authors declare that no experiments were performed
on humans or animals for this study.
Condentiality of data. The authors declare that no
patient data appear in this article.
Right to privacy and informed consent. The authors
declare that no patient data appear in this article.
References
1. Frank MG, Brain Rhythms. In: Binder MD, Hirokawa N, Windhorst U,
editors. Encyclopedia of Neuroscience. Berlin, Heidelberg: Springer; 2008.
2. Rechtschaffen A, Kales A. AManual of Standardized Terminology, Te-
chniques and Scoring System for Sleep Stages of Human Subjects. Los
Angeles (Calif.): University of California. Brain Research Institute; 1968.
3. Siever D. The application of audiovisual entrainment for the treatment of
seasonal affective disorder. Biofeedback. 2004:32:32-5.
4. Gruzelier JH. New advances in EEG and cognition. Int J Psychophysiol.
1996;24:1-5.
5. Foster DS. EEG and Subjective Correlates of Alpha Frequency Binaural
Beats Stimulation Combined with Alpha Biofeedback. Ann Arbor, MI:
UMI; 1990.
6. Kennerly RC. An Empirical Investigation into the Effect of Beta Frequen-
cy Binaural Beat Audio Signals on Four Measures of Human Memory.
Carrolton, Georgia: Department of Psychology, West Georgia College;
1994. Available from https://www.iawakepro.com/an-empirical-investiga-
tion-into-the-effect-of-beta-frequency-binaural-beat-audio-signals-on-
four-measures-of-human-memory.
No part of this publication may be reproduced or photocopying without the prior written permission of the publisher. © Permanyer 2021
247
S. Aparecido-Kanzler, et al.: Binaural and isochronic tones in brain
7. Le Scouranec RP, Poirier RM, Owens JE, Gauthier J, Taylor AG,
Foresman PA. Use of binaural beat tapes for treatment of anxiety: a pilot
study of tape preference and outcomes. Altern Ther. 2001;7:58-63.
8. Granada AE, Herzel H. How to achieve fast entrainment? The timescale
to synchronization. PLoS One. 2009;4:e7057.
9. Huygens C. Horologium Oscillatorium sive de motu pendulorum ad ho-
rologia aptato demonstrationes geometricae. Paris, France: Apud F.
Muguet; 1673. The Pendulum Clock Ames: Iowa State University Press;
1986.
10. Oster G. Auditory beats in the brain. Sci Am. 1973;229:94-102.
11. Cannon J, McCarthy MM, Lee S, Lee J, Börgers C, Whittington MA, etal.
Neurosystems: brain rhythms and cognitive processing. Eur J Neurosci.
2014;39:705-19.
12. Bear M, Connors BW, Paradiso MA. Unraveling the Nervous System.
10thed. Porto Alegre, Brazil: Artmed; 2017.
13. Apa-Soeta Y, Nakagawa S. Effects of the binaural auditory filter in the
human brain. Neuro Report. 2007;18:1939-43.
14. Monroe RA, Gabbard GO, Jones FC, Twemlow SW. Far Journeys. Gar-
den City, NY: Doubleday; 1985.
15. Kasprzak C. Influence of binaural beats on EEG signal. Acta Phys Pol.
2011;119:986-90.
16. Zampi DD. Efficacy of theta binaural beats for the treatment of chronic
pain. Altern Ther Health Med. 2016;22:32-8.
17. Becher AK, Höhne M, Axmacher N, Chaieb L, Elger CE, Fell J. Intracra-
nial electroencephalography power and phase synchronization changes
during monaural and binaural beat stimulation. Eur J Neurosci.
2015;41:254-63.
18. Jirakittayakorn N, Wongsawat Y. The brain responses to different fre-
quencies of binaural sounds on QEEG at cortical level. Conf Proc IEEE
Eng Med Biol Soc. 2015;4687-91.
19. Higgins J, Thomas J, editors. Cochrane Handbook for Systematic Re-
views of Interventions; 2019. Available from: https://www.training.cochra-
ne.org/handbook/current. [Last accessed on 2019Oct 12].
20. Jadad AR, Moore RA, Carroll D, Jenkinson C, Reynolds DJ, GavaghanDJ,
et al. Assessing the quality of reports of randomized clinical trials: is
blinding necessary? Control Clin Trials. 1996;17:1-12.
21. Washington P, Pit-Claudel B, Paredes P. Mental Health Interventions
through Brain Wave Oscillations. In: Proceedings of SIGCHI 19 (Compu-
ting and Mental Health Symposium). NewYork: ACM; 2019.
22. Szentirmai E, Yasuda T, Taishi P, Wang M, Churchill L, Bohnet S, et al.
Growth hormone-releasing hormone: cerebral cortical sleep-related EEG
actions and expression. Am J Physiol Regul Integr Comp Physiol.
2007;293:R922-30.
23. Botella-Soler V, Valderrama M, Benoît C, Navarro M, Quyen LV. Lar-
ge-scale cortical dynamics of sleep slow waves. PLoS One. 2012;
7:e30757.
24. Wickramasekera IE. On attempts to modify hypnotic susceptibility: some
psychophysiological procedures and promising directions. Ann N Y Acad
Sci. 1977;296:143-53.
25. Sabourin M, Cutcomb SD, Crawford HJ, Pribram K. EEG correlates of
hypnotic susceptibility and hypnotic trance: spectral analysis and cohe-
rence Int J Psychophysiol. 1990;10:125-42.
26. Derner M, Chaieb L, Surges R, Staresina BP, Fell J. Modulation of item
and source memory by auditory beat stimulation: a pilot study with intra-
cranial EEG. Front Hum Neurosci. 2018;12:500.
27. Garcia-Argibay M, Santed MA, Reales JM. Binaural Auditory beats affect
long-term memory. Psychol Res. 2019;83:1124-36.
28. Beauchene C, Abaid N, Moran R, Diana RA, Leonessa A. The effect of
binaural beats on visuospatial working memory and cortical connectivity.
PLoS One. 2016;11:e0166630.
29. Beauchene C, Abaid N, Moran R, Diana RA, Leonessa A. The effect of
binaural beats on verbal working memory and cortical connectivity.
JNeural Eng. 2017;14:026014.
30. McConnell PA, Froeliger B, Garland EL, Ives JC, Sforzo GA. Auditory
driving of the autonomic nervous system: listening to theta-frequency
binaural beats post-exercise increases parasympathetic activation and
sympathetic withdrawal. Front Psychol. 2014;5:1248.
31. Chaieb L, Wilpert EC, Hoppe C, Axmacher N, Fell J. The impact of
monaural beat stimulation on anxiety and cognition. Front Hum Neuros-
ci. 2017;11:251.
32. Bhat P. Efficacy of Alfa EEG wave biofeedback in the management of
anxiety. Ind Psychiatry J. 2010;19:111-4.
33. Klimesch W. EEG alpha and theta oscillations reflect cognitive and me-
mory performance: a review and analysis. Brain Res Brain Res Rev.
1999;29:169-95.
34. Vernon D, Peryer G, Louch J, Shaw M. Tracking EEG changes in respon-
se to alpha and beta binaural beats. Int J Psychophysiol. 2014;93:134-9.
35. Tirdad SA, Ahmadi-Pajouh MA, Nasrabadi AM. Cumulative effects of
theta binaural beats on brain power and functional connectivity. Biomed
Sig Proc Control 2018;42:242-52.
36. Reedijk SA, Bolders A, Colzato LS, Hommel B. Eliminating the attentional
blink through binaural beats: a case for tailored cognitive enhancement.
Front Psychiatry. 2015;6:82.
37. Brenner RP, Ulrich RF, Spiker DG, Sclabassi RJ, Reynolds CF 3rd,
MarinRS, et al. Computerized EEG spectral analysis in elderly normal,
demented and depressed subjects. Electroencephalogr Clin Neurophy-
siol. 1986;64:483-92.
38. Hauri P. Treating psychophysiologic insomnia with biofeedback. Arch
Gen Psychiatry. 1981;38:752-8.
39. Howard CE, Graham LE 2nd, Wycoff SJ. Acomparison of methods for
reducing stress among dental students. JDent Educ. 1986;50:542-4.
40. Graham J. Patrick RN. Improved neuronal regulation in ADHD. JNeuro-
ther. 1996;1:27-36.
41. Egner T, Gruzelier JH. EEG biofeedback of low beta band components:
frequency-specific effects on variables of attention and event-related
brain potentials. Clin Neurophysiol. 2004;115:131-9.
42. Neto JD. Neurofeedback How Neuropsicoterapia Appeal to The Deficit
Disorder Attention with or Without Hyperactivity and Impulsivity. Teresina,
Brazil: Revista FSA (Faculdade Santo Agostinho); 2012.
43. Gálvez G, Recuero M, Canuet L, Del-Pozo F. Short-term effects of bin-
aural beats on EEG power, functional connectivity, cognition, gait and
anxiety in parkinson’s disease. Int J Neural System. 2018;28:1750055.
44. Kennel S, Taylor AG, Lyon D, Bourguignon C. Pilot feasibility study of
binaural auditory beats for reducing symptoms of inattention in children
and adolescents with attention-deficit/hyperactivity disorder. J Pediatr
Nurs. 2010;25:3-11.
45. Munk MH, Roelfsema PR, König P, Engel AK, Singer W. Role of reticu-
lar activation in the modulation of intracortical synchronization. Science.
1996;272:271-4.
46. Burle B, Bonnet M. High-speed memory scanning: a behavioral argument
for a serial oscillatory model. Brain Res Cogn Brain Res. 2000;9:327-37.
47. John ER, Prichep LS, Kox W, Valdés-Sosa P, Bosch-Bayard J, AubertE,
et al. Invariant reversible QEEG effects of anesthetics. Conscious Cogn.
2001;10:165-83.
48. Davidson RJ, McEwen BS. Social influences on neuroplasticity: stress
and interventions to promote well-being. Nat Neurosci. 2012;15:689-95.
49. Miltner WH, Braun C, Arnold M, Witte H, Taub E. Coherence of gamma-band
EEG activity as a basis for associative learning. Nature. 1999;397:434-6.
50. Crone NE, Hao L, Hart J Jr., Boatman D, Lesser RP, Irizarry R, et al.
Electrocorticographic gamma activity during word production in spoken
and sign language. Neurology. 2001;57:2045-53.
51. Benson H. Transcendental meditation science or cult? JAMA. 1974;227:807.
52. Jirakittayakorn N, Wongsawat Y. Brain responses to 40-Hz binaural beat
and effects on emotion and memory. Int J Psychophysiol. 2017;120:96-107.
53. Colzato LS, Steenbergen L, Sellaro R. The effect of gamma-enhancing
binaural beats on the control of feature bindings. Exp Brain Res.
2017;235:2125-31.
54. Colzato LS, Barone H, Sellaro R, Hommel B. More attentional focusing through
binaural beats: evidence from the global-local task. Psychol Res. 2017;81:271-7.
55. Chaieb L, Leszczynski M, Axmacher N, Höhne M, Elger CE, Fell J.
Theta-gamma phase-phase coupling during working memory maintenan-
ce in the human hippocampus. Cogn Neurosci. 2015;6:149-57.
56. Lent, R, One Hundred Billion Neurons: Fundamental Concepts of Neu-
roscience. São Paulo: Atheneu; 2004.
57. Poulet JF, Fernandez LM, Crochet S, Petersen CC. Thalamic control of
cortical states. Nat Neurosci. 2012;15:370-2.
58. López-Caballero F, Escera C. Enhancement of gamma-band electroen-
cephalographic activity (solely) by binaural beats Binaural beat: a failure
to enhance EEG power and emotional arousal. Front Hum Neurosci.
2017;11:557.
No part of this publication may be reproduced or photocopying without the prior written permission of the publisher. © Permanyer 2021
ResearchGate has not been able to resolve any citations for this publication.
Book
Full-text available
The revised edition of the Handbook offers the only guide on how to conduct, report and maintain a Cochrane Review. The second edition of The Cochrane Handbook for Systematic Reviews of Interventions contains essential guidance for preparing and maintaining Cochrane Reviews of the effects of health interventions. Designed to be an accessible resource, the Handbook will also be of interest to anyone undertaking systematic reviews of interventions outside Cochrane, and many of the principles and methods presented are appropriate for systematic reviews addressing research questions other than effects of interventions. This fully updated edition contains extensive new material on systematic review methods addressing a wide-range of topics including network meta-analysis, equity, complex interventions, narrative synthesis, and automation. Also new to this edition, integrated throughout the Handbook, is the set of standards Cochrane expects its reviews to meet. Written for review authors, editors, trainers and others with an interest in Cochrane Reviews, the second edition of The Cochrane Handbook for Systematic Reviews of Interventions continues to offer an invaluable resource for understanding the role of systematic reviews, critically appraising health research studies and conducting reviews.
Article
Full-text available
Auditory beat stimulation is an upcoming technique for non-invasive brain stimulation. Its influence on mediotemporal regions and memory processes has not yet been thoroughly investigated. A recent study suggests that auditory beats are able to alter intracranial EEG (iEEG) power and phase synchronization. 5 Hz binaural beat stimulation increased temporo-lateral phase synchronization, while 5 Hz monaural beat stimulation decreased mediotemporal synchronization. Based on the relevance of phase synchronization for memory operations, we hypothesized that 5 Hz binaural beat stimulation enhances, while 5 Hz monaural beat stimulation decreases long-term memory performance. We analyzed data from presurgical epilepsy patients with implanted depth electrodes in the hippocampus and rhinal cortex. 5 Hz monaural and binaural beat vs. control stimulation was applied while patients performed an associative learning task involving item and source recognition. We evaluated behavioral effects for item (hits minus false alarms) and source memory (correct minus incorrect) and the impact of auditory beats on iEEG power, rhinal-hippocampal phase synchronization and inter-trial phase locking. A three-way repeated measures ANOVA (encoding/retrieval, item/source, monaural/binaural/control) revealed a main effect of stimulation (p = 0.03) and a linear effect in the expected direction: binaural > control > monaural (p = 0.036). Both monaural and binaural stimulation were associated with increased phase locking of 5 Hz oscillations within rhinal cortex. These phase locking increases, however, corresponded to reverse phase shifts. Our data suggest that binaural vs. monaural 5 Hz stimulation increases vs. decreases long-term memory performance. These behavioral effects appear to be related to reverse phase shifts within rhinal cortex.
Article
Full-text available
The presentation of two pure tones to each ear separately with a slight difference in their frequency results in the perception of a single tone that fluctuates in amplitude at a frequency that equals the difference of interaural frequencies. This perceptual phenomenon is known as binaural auditory beats, and it is thought to entrain electrocortical activity and enhance cognition functions such as attention and memory. The aim of this study was to determine the effect of binaural auditory beats on long-term memory. Participants (n = 32) were kept blind to the goal of the study and performed both the free recall and recognition tasks after being exposed to binaural auditory beats, either in the beta (20 Hz) or theta (5 Hz) frequency bands and white noise as a control condition. Exposure to beta-frequency binaural beats yielded a greater proportion of correctly recalled words and a higher sensitivity index dʹ in recognition tasks, while theta-frequency binaural-beat presentation lessened the number of correctly remembered words and the sensitivity index. On the other hand, we could not find differences in the conditional probability for recall given recognition between beta and theta frequencies and white noise, suggesting that the observed changes in recognition were due to the recollection component. These findings indicate that the presentation of binaural auditory beats can affect long-term memory both positively and negatively, depending on the frequency used.
Article
Full-text available
When two pure tones of slightly different frequencies are delivered simultaneously to the two ears, is generated a beat whose frequency corresponds to the frequency difference between them. That beat is known as acoustic beat. If these two tones are presented one to each ear, they still produce the sensation of the same beat, although no physical combination of the tones occurs outside the auditory system. This phenomenon is called binaural beat. In the present study, we explored the potential contribution of binaural beats to the enhancement of specific EEG bands, as previous studies suggest the potential usefulness of binaural beats as a brainwave entrainment tool. Additionally, we analyzed the effects of binaural-beat stimulation on two psychophysiological measures related to emotional arousal: heart rate and skin conductance. Beats of five different frequencies (4.53 Hz -theta-, 8.97 Hz -alpha-, 17.93 Hz -beta-, 34.49 Hz -gamma- or 57.3 Hz -upper-gamma) were presented binaurally and acoustically for epochs of 3 minutes (Beat epochs), preceded and followed by pink noise epochs of 90 seconds (Baseline and Post epochs, respectively). In each of these epochs, we analyzed the EEG spectral power, as well as calculated the heart rate and skin conductance response. For all the beat frequencies used for stimulation, no significant changes between Baseline and Beat epochs were observed within the corresponding EEG bands, neither with binaural or with acoustic beats. Additional analysis of spectral EEG topographies yielded negative results for the effect of binaural beats in the scalp distribution of EEG spectral power. In the psychophysiological measures, no changes in heart rate and skin conductance were observed for any of the beat frequencies presented. Our results do not support binaural-beat stimulation as a potential tool for the enhancement of EEG oscillatory activity, nor to induce changes in emotional arousal
Article
Full-text available
We applied rhythmic binaural sound to Parkinson's Disease (PD) patients to investigate its influence on several symptoms of this disease and on Electrophysiology (Electrocardiography and Electroencephalography (EEG)). We conducted a double-blind, randomized controlled study in which rhythmic binaural beats and control were administered over two randomized and counterbalanced sessions (within-subjects repeated-measures design). Patients ([Formula: see text], age [Formula: see text], stage I-III Hoehn & Yahr scale) participated in two sessions of sound stimulation for 10[Formula: see text]min separated by a minimum of 7 days. Data were collected immediately before and after both stimulations with the following results: (1) a decrease in theta activity, (2) a general decrease in Functional Connectivity (FC), and (3) an improvement in working memory performance. However, no significant changes were identified in the gait performance, heart rate or anxiety level of the patients. With regard to the control stimulation, we did not identify significant changes in the variables analyzed. The use of binaural-rhythm stimulation for PD, as designed in this study, seems to be an effective, portable, inexpensive and noninvasive method to modulate brain activity. This influence on brain activity did not induce changes in anxiety or gait parameters; however, it resulted in a normalization of EEG power (altered in PD), normalization of brain FC (also altered in PD) and working memory improvement (a normalizing effect). In summary, we consider that sound, particularly binaural-rhythmic sound, may be a co-assistant tool in the treatment of PD, however more research is needed to consider the use of this type of stimulation as an effective therapy.
Article
Full-text available
Application of auditory beat stimulation has been speculated to provide a promising new tool with which to alleviate symptoms of anxiety and to enhance cognition. In spite of reportedly similar EEG effects of binaural and monaural beats, data on behavioral effects of monaural beats are still lacking. Therefore, we examined the impact of monaural beat stimulation on anxiety, mood and memory performance. We aimed to target states related to anxiety levels and general well-being, in addition to long-term and working memory processes, using monaural beats within the range of main cortical rhythms. Theta (6 Hz), alpha (10 Hz) and gamma (40 Hz) beat frequencies, as well as a control stimulus were applied to healthy participants for 5 min. After each stimulation period, participants were asked to evaluate their current mood state and to perform cognitive tasks examining long-term and working memory processes, in addition to a vigilance task. Monaural beat stimulation was found to reduce state anxiety. When evaluating responses for the individual beat frequencies, positive effects on state anxiety were observed for all monaural beat conditions compared to control stimulation. Our results indicate a role for monaural beat stimulation in modulating state anxiety and are in line with previous studies reporting anxiety-reducing effects of auditory beat stimulation.
Article
Full-text available
Binaural beats represent the auditory experience of an oscillating sound that occurs when two sounds with neighboring frequencies are presented to one’s left and right ear separately. Binaural beats have been shown to impact information processing via their putative role in increasing neural synchronization. Recent studies of feature-repetition effects demonstrated interactions between perceptual features and action-related features: repeating only some, but not all features of a perception–action episode hinders performance. These partial-repetition (or binding) costs point to the existence of temporary episodic bindings (event files) that are automatically retrieved by repeating at least one of their features. Given that neural synchronization in the gamma band has been associated with visual feature bindings, we investigated whether the impact of binaural beats extends to the top-down control of feature bindings. Healthy adults listened to gamma-frequency (40 Hz) binaural beats or to a constant tone of 340 Hz (control condition) for ten minutes before and during a feature-repetition task. While the size of visuomotor binding costs (indicating the binding of visual and action features) was unaffected by the binaural beats, the size of visual feature binding costs (which refer to the binding between the two visual features) was considerably smaller during gamma-frequency binaural beats exposure than during the control condition. Our results suggest that binaural beats enhance selectivity in updating episodic memory traces and further strengthen the hypothesis that neural activity in the gamma band is critically associated with the control of feature binding.
Article
Audiovisual stimuli with specific frequency can cause the brain to oscillate in the same frequency, something which is also called brain entrainment. One method to entrain the brain through the auditory system is binaural beats. Binaural beats are two rhythmic tones with slightly different frequency which are presented separately to each ear. The brain perceives an illusionary signal with the frequency of the difference of the two exerted tones and oscillates in that frequency. There are contradictory findings in the previous studies in which some researchers could not entirely observe this phenomenon. In this paper we propose a protocol to inspect whether binaural beats can change the power and connectivity of the brain and also how lengthening the stimuli, interchangeably with pink noise, will affect the outcomes. Fifteen healthy participants attended this study and their EEG signals were recorded during presentation of 200 Hz and 207 Hz sinusoidal tones to their left and right ears respectively. Total 9 min of binaural beats were divided into three 3-min blocks which were separated by 1 min of pink noise to prevent the brain from habituating to the stimuli. Our results showed that 3 min of 7 Hz binaural beats is not enough to entrain the brain, but applying 6 min of stimulation could change the relative power in the temporal and parietal lobes and further exposure to 9 min of stimuli could also alter the brain network, evaluated by the graph theory.
Article
Gamma oscillation plays a role in binding process or sensory integration, a process by which several brain areas beside primary cortex are activated for higher perception of the received stimulus. Beta oscillation is also involved in interpreting received stimulus and occurs following gamma oscillation, and this process is known as gamma-to-beta transition, a process for neglecting unnecessary stimuli in surrounding environment. Gamma oscillation also associates with cognitive functions, memory and emotion. Therefore, modulation of the brain activity can lead to manipulation of cognitive functions. The stimulus used in this study was 40-Hz binaural beat because binaural beat induces frequency following response. This study aimed to investigate the neural oscillation responding to the 40-Hz binaural beat and to evaluate working memory function and emotional states after listening to that stimulus. Two experiments were developed based on the study aims. In the first experiment, electroencephalograms were recorded while participants listened to the stimulus for 30 min. The results suggested that frontal, temporal, and central regions were activated within 15 min. In the second experiment, word list recall task was conducted before and after listening to the stimulus for 20 min. The results showed that, after listening, the recalled words were increase in the working memory portion of the list. Brunel Mood Scale, a questionnaire to evaluate emotional states, revealed changes in emotional states after listening to the stimulus. The emotional results suggested that these changes were consistent with the induced neural oscillations.