ble at ScienceDirect

Journal of Traditional and Complementary Medicine 6 (2016) 23e28
Contents lists availa
HOSTED BY

Journal of Traditional and Complementary Medicine

journal homepage: http: / /www.elsevier .com/locate/ j tcme
Original article
Effects of auditory stimulation with music of different intensities on
heart period

Joice A.T. do Amaral a, Heraldo L. Guida a, Luiz Carlos de Abreu b, Viviani Barnab�e c,
Franciele M. Vanderlei d, Vitor E. Valenti a, *

a Faculdade de Filosofia e Ciências, Universidade Estadual Paulista, Marília, S~ao Paulo, Brazil
b Faculdade de Medicina do ABC, Santo Andr�e, S~ao Paulo, Brazil
c Harvard Medical School of Public Health, Boston, MA, USA
d Faculdade de Ciências e Tecnologia, Universidade Estadual Paulista, Presidente Prudente, S~ao Paulo, Brazil
a r t i c l e i n f o

Article history:
Received 7 October 2014
Received in revised form
5 November 2014
Accepted 16 November 2014
Available online 7 January 2015

Keywords:
auditory stimulation
autonomic nervous system
cardiovascular system
heart rate variability
music
* Corresponding author. Faculdade de Filosofia e Ci
Paulista, UNESP Av. HyginoMuzzi Filho 737, 17525-00

E-mail address: vitor.valenti@gmail.com (V.E. Vale
Peer review under responsibility of The Center

National Taiwan University.

http://dx.doi.org/10.1016/j.jtcme.2014.11.032
2225-4110/Copyright © 2014, Center for Food and Bio
a b s t r a c t

Various studies have indicated that music therapy with relaxant music improves cardiac function of
patients treated with cardiotoxic medication and heavy-metal music acutely reduces heart rate vari-
ability (HRV). There is also evidence that white noise auditory stimulation above 50 dB causes cardiac
autonomic responses. In this study, we aimed to evaluate the acute effects of musical auditory stimu-
lation with different intensities on cardiac autonomic regulation. This study was performed on 24
healthy women between 18 and 25 years of age. We analyzed HRV in the time [standard deviation of
normal-to-normal RR intervals (SDNN), percentage of adjacent RR intervals with a difference of duration
>50 ms (pNN50), and root-mean square of differences between adjacent normal RR intervals in a time
interval (RMSSD)] and frequency [low frequency (LF), high frequency (HF), and LF/HF ratio] domains.
HRV was recorded at rest for 10 minutes. Subsequently, the volunteers were exposed to baroque or
heavy-metal music for 5 minutes through an earphone. The volunteers were exposed to three equivalent
sound levels (60e70, 70e80, and 80e90 dB). After the first baroque or heavy-metal music, they
remained at rest for 5 minutes and then they were exposed to the other music. The sequence of songs
was randomized for each individual. Heavy-metal musical auditory stimulation at 80e90 dB reduced the
SDNN index compared with control (44.39 ± 14.40 ms vs. 34.88 ± 8.69 ms), and stimulation at 60e70 dB
decreased the LF (ms2) index compared with control (668.83 ± 648.74 ms2 vs. 392.5 ± 179.94 ms2).
Baroque music at 60e70 dB reduced the LF (ms2) index (587.75 ± 318.44 ms2 vs. 376.21 ± 178.85 ms2). In
conclusion, heavy-metal and baroque musical auditory stimulation at lower intensities acutely reduced
global modulation of the heart and only heavy-metal music reduced HRV at higher intensities.
Copyright © 2014, Center for Food and Biomolecules, National Taiwan University. Production and hosting

by Elsevier Taiwan LLC. All rights reserved.
1. Introduction

Auditory stimulation with music as a therapy has received
attention for treatment and prevention of disorders.1 Studies on
music therapy were performed on patients under pharmacological
treatment, immediately after surgery or awaiting surgical pro-
cedures.2 Musical auditory stimulation produces an extensive
ências, Universidade Estadual
0 Marília, SP, Brazil.
nti).
for Food and Biomolecules,

molecules, National Taiwan Unive
variety of psychological and hemodynamic effects by influencing
the cardiac autonomic modulation.3,4

In this regard, heart rate variability (HRV) is a method that ana-
lyzes the oscillations of the intervals between consecutive heartbeats
(RR intervals). HRV is well accepted in the literature to investigate
cardiac autonomic regulation,which is influencedby the sinus node.5

Reduction inHRV is an indicatorof poor cardiovascular function, such
as in the case of chronic heart failure, whereas the increase in HRV
corresponds to an improvement of cardiovascular function.6

Patients with cancer treated with anthracycline, a cardiotoxic
medication, had improvements in HRV after music therapy inter-
vention for 10 weeks. However, after the treatment cessation, their
HRV levels returned to control values reported before the music
therapy intervention, indicating the positive effects of music
rsity. Production and hosting by Elsevier Taiwan LLC. All rights reserved.

Delta:1_given name
Delta:1_surname
Delta:1_given name
Delta:1_surname
Delta:1_given name
Delta:1_surname
mailto:vitor.valenti@gmail.com
http://crossmark.crossref.org/dialog/?doi=10.1016/j.jtcme.2014.11.032&domain=pdf
www.sciencedirect.com/science/journal/22254110
http://www.elsevier.com/locate/jtcme
http://dx.doi.org/10.1016/j.jtcme.2014.11.032
http://dx.doi.org/10.1016/j.jtcme.2014.11.032
http://dx.doi.org/10.1016/j.jtcme.2014.11.032


J.A.T. do Amaral et al. / Journal of Traditional and Complementary Medicine 6 (2016) 23e2824
therapy on HRV in that population.3 Another study suggested that
music therapy increased parasympathetic activity and reduced the
probability of congestive heart failure development in elderly pa-
tients with dementia and cerebrovascular disease.7

Although it was already evidenced that acoustic stimulation
withwhite noise above 50 dB caused cardiac sympathetic changes,8

it is not well understood whether the effects of musical auditory
stimulation on HRV are dependent on equivalent sound level.
Moreover, knowledge on cardiac autonomic responses elicited by
music exposure is important for developing future therapies that
might contribute to the prevention of cardiovascular disorders.
Therefore, in this study, we evaluated the acute effects of baroque
and heavy-metal musical auditory stimulation at different in-
tensities on cardiac autonomic regulation.

2. Methods

2.1. Study population

Volunteers were 28 healthy female college students (all non-
smokers; age,18e25 years). All volunteers were informed about the
procedures and objectives of the study and gave written informed
consent. All study procedures were approved by the Ethics Com-
mittee in Research of the Faculty of Sciences of the Universidade
Estadual Paulista, Campus de Marilia (No. Protocol: 2011-385), and
were in accordance with Resolution 196/96 National Health 10/10/
1996.

2.2. Noninclusion criteria

Volunteers were excluded if they had cardiopulmonary, audi-
tory, psychological, and neurological disorders, and other impair-
ments that would prevent them from performing the study
procedures. We also excluded those undergoing treatment with
drugs that influence cardiac autonomic regulation.

2.3. Initial evaluation

Baseline criteria for initial evaluation were age, sex, weight,
height, and bodymass index (BMI). Weight was determined using a
digital scale (W 200/5; Welmy Ind Com Ltda, S~ao Paulo, Brazil) with
a precision of 0.1 kg. Height was determined using a stadiometer
(ES 2020; Sanny, S~ao Paulo, Brazil) with a precision of 0.1 cm and
extension of 2.20 m. BMI was calculated as weight/height,2 with
weight in kilograms and height in meters.

2.4. Measurement of the auditory stimulation

Measurements of the equivalent sound levels were conducted in
a soundproof room using an SV 102 audio dosimeter (Svantek,
Warsaw, Poland). This device was programmed to take measure-
ments in the “A” weighting circuit with a slow response.

Measurements were taken when participants relaxed for 10
minutes by listening to classical baroque music. An insert-type
microphone (microphone in real ear) was placed inside the audi-
tory canal of the volunteer, just below the speaker, which was
connected to a personal stereo.

Before each measurement, the microphone was calibrated with
an acoustic CR:514 model calibrator (Cirrus Research).

For the analysis, we used Leq (A), which is defined as the
equivalent sound pressure level and which corresponds to the
constant sound level in the same time interval. It contains the same
total energy as the sound. We also analyzed the frequency spec-
trum of the sound stimulation (octave band).9
2.5. HRV analysis

The RR intervals recorded by the portable RS800CX HR monitor
(sampling rate, 1000 Hz) were downloaded to the Polar Precision
Performance program (version 3.0; Polar Electro, Kempele,
Finland). This software enabled the visualization of HR and the
extraction of a cardiac period (RR interval) file in “.txt” format.
Following digital filtering complemented with manual filtering for
the elimination of premature ectopic beats and artifacts, at least
256 RR intervals were used for the data analysis. Only those series
with more than 95% sinus rhythm were included in the study.5 For
calculation of the linear indices, we used the HRV analysis software
(Kubios HRV version 1.1 for Windows; Biomedical Signal Analysis
Group, Department of Applied Physics, University of Kuopio, Kuo-
pio, Finland).

2.6. Linear indices of HRV

To analyze HRV in the frequency domain, the low frequency
(LF ¼ 0.04e0.15 Hz) and high frequency (HF ¼ 0.15e0.40 Hz)
spectral components were measured in m/s and normalized units,
representing a value relative to each spectral component in relation
to the total power minus the very-low-frequency components, and
the ratio between these components (LF/HF). The spectral analysis
was performed using the fast Fourier transform algorithm.10

The time domain analysis was performed in terms of standard
deviation of normal-to-normal RR intervals (SDNN), percentage of
adjacent RR intervals with a difference of duration > 50 ms
(pNN50), and root-mean square of differences between adjacent
normal RR intervals in a time interval (RMSSD).

We used Kubios HRV version 2.0 software to analyze these
indices.11

2.7. Protocol

Data collectionwas carried out in the same soundproof room for
all volunteers with the temperature between 21�C and 25�C and
relative humidity between 50% and 60%. All volunteers were
instructed not to drink alcohol and caffeine for 24 hours before
evaluation. Data were collected on an individual basis, between 8
and 12 AM to standardize the protocol. All procedures necessary for
data collection were explained to every volunteer individually. The
volunteers were instructed to remain at rest and avoid talking
during the data collection.

After the initial evaluation, the heart monitor belt was placed
over the thorax, aligned with the distal third of the sternum, and
the Polar RS800CX HR receiver (Polar Electro) was placed on the
wrist. The volunteers (eyes opened) wore headphones and avoided
tapping with a finger or a foot (to avoid art factual entrainment),
which was confirmed by continuous visual monitoring.

The women variables were compared between the following:
(1) rest control; (2) music at 60e70 dB; (3) music at 70e80 dB; and
(4) music at 80e90 dB. The musical auditory stimulation was per-
formed using an excitatory heavymetal (Gamma Ray: “HeavyMetal
Universe”) and a relaxant baroque (Pachelbel: “Canon” in D Major;
an example of the first nine measures in shown in Fig. 1). The
sequence of intensity of songs was randomized for each individual.

2.8. Statistical analysis

Standard statistical methods were used to calculate the means
and standard deviations. The normal Gaussian distribution of the
datawas verified by the ShapiroeWilk goodness-of-fit test (z > 1.0).
For parametric distributions, we applied analysis of variance for
repeated measures followed by the Bonferroni post-test. For



Fig. 1. The first nine measures of the Canon in D. Colors highlight the individual canonic entries. Note. Edited from “Johann Pachelbel: Organist, Teacher, Composer, A Critical
Reexamination of His Life, Works, and Historical Significance [dissertation],” by K.J. Welter, 1998. Cambridge, MA: Harvard University; 1998.

J.A.T. do Amaral et al. / Journal of Traditional and Complementary Medicine 6 (2016) 23e28 25
nonparametric distributions, we used the Friedman test followed
by Dunn post-test. Differences were considered significant when
the probability of a Type I error was less than 5% (p < 0.05). We used
BioStat 2009 Professional 5.8.4 software for statistical analysis.
3. Results

Data on baseline systolic arterial pressure, diastolic arterial
pressure, HR, mean RR interval, age, height, body weight, and BMI
are presented in Table 1.

In relation to the time domain indices of HRV, we noted that the
SDNN index reduced during exposure to auditory stimulation with
heavy-metal music at 80e90 dB compared with the control con-
dition, whereas the RMSSD and pNN50 indices were not signifi-
cantly changed during exposure to heavy-metal musical auditory
stimulation at three equivalent sound levels (Table 2).

In Table 2, it can be seen that the LF domain index in absolute
units was decreased during heavy-metal musical auditory stimu-
lation at 60e70 dB compared with the control condition, whereas
no significant change was noted for the LF index in normalized
units, HF index in normalized and absolute units, and LF/HF ratio.

With regard to baroque musical auditory stimulation, the SDNN,
RMSSD, and pNN50 time domain indices of HRV were not signifi-
cantly changed during exposure to this music style at the three
equivalent sound levels (Table 3).

From Table 3, it can be seen that auditory stimulation with
baroque music style at 60e70 dB reduced the LF index in absolute
units. By contrast, the LF index in normalized units, HF index in
absolute and normalized units, and LF/HF ratio were not signifi-
cantly changed during exposure to this music style at the three
equivalent sound levels.

Fig. 2 shows an example of the visual evaluation of the power
spectrum density analysis observed in one volunteer before
Table 1
Baseline DAP, SAP, HR, mean RR, weight, height, and BMI of the
volunteers.

Variable Value

Age (y) 20.9 ± 2.2
Height (m) 1.6 ± 0.1
Weight (kg) 56.7 ± 7.3
BMI (kg/m2) 21.3 ± 2.7
HR (bpm) 82.55 ± 12.57
Mean RR (ms) 749.12 ± 140.05
SAP (mmHg) 110.4 ± 6.2
DAP (mmHg) 75 ± 8

BMI ¼ body mass index; DAP ¼ diastolic arterial pressure;
HR ¼ heart rate; mean RR ¼ mean RR interval; SAP ¼ systolic
arterial pressure.
exposure to baroque musical auditory stimulation, during music
exposure between 60 and 70 dB, during music exposure between
70 and 80 dB, and during music exposure between 80 and 90 dB.

Fig. 3 presents an example of power spectrum density analysis
in one volunteer before exposure to heavy-metal musical auditory
stimulation, during music exposure between 60 and 70 dB, during
music exposure between 70 and 80 dB, and during music exposure
between 80 and 90 dB (Fig. 3).
4. Discussion

The investigation of the intensity of musical auditory stimula-
tion is important to improve musical therapy for alternative
treatments.12 A recent study reported that white noise stimulation
above 50 dB heightened the sympathetic component of HR regu-
lation and also demonstrated significant association between the
LF/HF ratio and the equivalent sound leveldthe higher the sound
intensity the higher the sympathetic tone on the heart and the
lower the HRV.8 In this context, our investigation was undertaken
to evaluate the acute effects of auditory stimulation with distinct
music styles of different intensities on cardiac autonomic regula-
tion. Interestingly, we noted that low-intensity (60e70 dB) heavy-
metal and baroque styles acutely reduced the frequency domain LF
index in absolute units, and the SDNN index in the time domain
was decreased during exposure to high-intensity (80e90 dB)
heavy-metal musical style.

We had previously reported that auditory stimulation with
Pachelbel's music between 60 and 70 dB decreased global modu-
lation of HR by reducing the LF index in absolute units. This index
corresponds to sympathetic and parasympathetic components of
the autonomic regulation of HR.13 A recent study showed that the
same music acutely reduced the same index in healthy women,14

but Canon in D music from Pachelbel had no significant effects on
cardiac autonomic regulation in previous studies.9,15 This contra-
dictory data may be explained by the difference between the study
methods. Roque et al14,15 also conducted studies on women who
were exposed to baroque music and subsequently to heavy-metal
music. It is possible that the sequence of music exposure influ-
enced the cardiac autonomic responses. In our study, however, we
did not select women in the luteal and follicular phases of the
menstrual cycle, whereas in the aforementioned studies this was
not a noninclusion criterion.

The baroque music chosen in our study was Canon in D from
Johann Pachelbel, a German composer of Protestant church music.
Canon in D from Pachelbel associates the techniques of canon and
ground bass. Canon is a polyphonic device in which several voices
play the same music, entering in sequence.16 Previous studies on
animals reported significant effects of different music on auto-
nomic nervous system. Rats under urethane anesthesia were



Table 2
Time and frequency domain indices before and after exposure to auditory stimulation with excitatory heavy-metal musical style.

Index Control 60e70 dB 70e80 dB 80e90 dB p

RMSSD 31.71 ± 14.2 30.31 ± 14.27 31.17 ± 12.64 30.1 ± 11.83 0.97
pNN50 13.37 ± 14.36 12.81 ± 15.7 13.11 ± 13.13 11.83 ± 12.07 0.98
SDNN 44.39 ± 14.4 35.09 ± 9.42 37.49 ± 10.09 34.88 ± 8.69a 0.01
HF (ms2) 516.33 ± 550.48 296.5 ± 245.61 350.88 ± 255.7 311.71 ± 215.97 0.11
LF (ms2) 668.83 ± 648.74 392.5 ± 179.94a 406.75 ± 241.37 411.58 ± 241.14 0.04
HF (nu) 42.44 ± 19.11 38.01 ± 17.91 42.53 ± 18.22 41.11 ± 18.82 0.82
LF (nu) 57.4 ± 19.11 61.52 ± 17.96 56.94 ± 18.34 58.38 ± 18.98 0.83
LF/HF 2.2 ± 2.93 2.43 ± 2.19 1.86 ± 1.57 2.28 ± 2.37 0.86

Data are presented as mean ± standard deviation.
HF ¼ high frequency; LF ¼ low frequency; LF/HF ¼ low frequency/high frequency ratio; pNN50 ¼ percentage of adjacent RR intervals with a difference of duration >50 ms;
RMSSD ¼ root-mean square of differences between adjacent normal RR intervals in a time interval; SDNN ¼ standard deviation of normal-to-normal RR intervals.

a Different from control.

Table 3
Time and frequency domain indices before and after exposure to auditory stimulation with baroque musical style.

Index Control 60e70 dB 70e80 dB 80e90 dB p

RMSSD 34.45 ± 16.46 29.29 ± 12.9 30.85 ± 13.72 31.2 ± 14.08 0.65
pNN50 15.21 ± 15.06 12.26 ± 13.51 12.78 ± 12.74 13.55 ± 14.72 0.89
SDNN 41.74 ± 10.23 35.9 ± 10.5 38.77 ± 13.23 37.96 ± 10.56 0.34
HF (ms2) 466.04 ± 405.06 356.33 ± 368.47 389.46 ± 336.15 361.46 ± 394.76 0.73
LF (ms2) 587.75 ± 318.44 376.21 ± 178.85a 462.17 ± 304.83 406.21 ± 216.02 0.03
HF (nu) 40.3 ± 21.5 41.3 ± 20.52 40.96 ± 19.1 40.39 ± 21.07 1.00
LF (nu) 58.65 ± 21.44 58.36 ± 20.62 58.88 ± 19.13 56.92 ± 20.94 0.99
LF/HF 2.46 ± 2.29 2.36 ± 2.83 2.10 ± 1.67 2.40 ± 2.24 0.95

Data are presented as mean ± standard deviation.
HF ¼ high frequency; LF ¼ low frequency; LF/HF ¼ low frequency/high frequency ratio; pNN50 ¼ percentage of adjacent RR intervals with a difference of duration >50 ms;
RMSSD ¼ root-mean square of differences between adjacent normal RR intervals in a time interval; SDNN ¼ standard deviation of normal-to-normal RR intervals.

a Different from control.

Fig. 2. Power spectrum density (PSD) analysis observed in one volunteer before exposure to baroque musical auditory stimulation, during music exposure between 60 and 70 dB,
during music exposure between 70 and 80 dB, and during music exposure between 80 and 90 dB.

J.A.T. do Amaral et al. / Journal of Traditional and Complementary Medicine 6 (2016) 23e2826
exposed to a relaxant music (“Tr€aumerei” from Kinderszenen
Op.15-7, R. Schumann) and an increase in gastric vagal nerve ac-
tivity was observed.17 Another study by the same group found that
the same music reduced sympathetic nerve activity and arterial
blood pressure in anesthetized rats and elucidated that some but
not all music can induce the same responses. This mechanism was
further investigated and the authors observed that this effect de-
pends on the intact auditory cortex and cochleae.18 The Pachelbel



Fig. 3. Power spectrum density (PSD) analysis observed in one volunteer before exposure to heavy-metal musical auditory stimulation, during music exposure between 60 and
70 dB, during music exposure between 70 and 80 dB, and during music exposure between 80 and 90 dB.

J.A.T. do Amaral et al. / Journal of Traditional and Complementary Medicine 6 (2016) 23e28 27
Canon in D music is not considered sedative. In this sense, we
suggest that we reported acute reduction of HRV in individuals
exposed to music with absence of relaxant rhythm.

According to our findings, heavy-metal musical auditory stim-
ulation reduced global modulation of HR at the highest intensity
(80e90 dB). The music used in our investigation was also reported
to reduce HRV in healthy women.14 Another previous study simi-
larly showed that healthy women had increased psychological re-
sponses to auditory stimulation with another heavy-metal music.19

The cardiac autonomic responses observed in our study are sug-
gested to be due to the excitatory feature of the heavy-metal music
style. We believe that the excitatory profile of heavy-metal music
associated with the high-equivalent sound level was responsible
for acutely decreasing HRV. Cardiac autonomic responses were
instantaneously elicited by low-intensity (50 dBA) white noise.

Lee et al8 observed a significant interaction between the cardiac
sympathetic modulation and white noise intensitydthe higher the
white noise intensity the higher the LF/HF ratio and the lower the
HRV. The association between noise intensity and activity of auto-
nomic nervous system is based on the acoustic startle reflex. This
reflex is a sudden response of arterial bloodpressure andHR induced
by an unexpected loud auditory stimulation.20 This reflex can cause
an immediate inhibition of muscle sympathetic nerve activity, and
the magnitude of the arterial blood pressure reaction is inversely
associated with the intensity of early muscle sympathetic nerve ac-
tivity inhibition.21 Taken together, we may surmise that the reduced
HRV elicited by high-intensity heavy-metal music was elicited by an
autonomic response involved in the acoustic startle reflex.

Our results showed that musical auditory stimulation with
baroque and heavy-metal styles between 60 and 70 dB decreased
global modulation of HR in healthy women. This data is supported
by the study results of Lee et al,8 who observed that cardiac auto-
nomic responses induced by binaural exposure to white noise
above 50 dB continuously for 5 minutes decreased HRV. In another
study, healthy women were exposed to white noise at 90 dB and
they were reported to have reduced parasympathetic regulation of
HR and no significant changes in the sympathovagal balance
through analysis of the LF/HF ratio.14 It is worth mentioning the
difference between baroque or excitatory heavy-metal musical
stimulation and white noise. Music has a high range of intensity,
whereas white noise is characterized by a small range in its
equivalent sound level.22 Furthermore, white noise has no signifi-
cant effect on the cognitive system, whereas musical auditory
stimulation affects emotions and memory,23,24 which in turn is
related to cardiac autonomic regulation.25 In this circumstance, we
suggest that the cardiac parasympathetic and sympathetic re-
sponses depend on the style of acoustic stimulation.

Based on our data, there was a relationship between the music
intensity and the overall variability of HR, becausewe found reduced
HRV during acute exposure to baroque and heavy-metal musical
auditory stimulation between 60 and 70 dB, and in addition, heavy
metal decreased HRV between 80 and 90 dB, whereas no significant
responses were noted when bothmusic styles were played between
70 and 80 dB. To avoid the effect ofmusic intensity sequence onHRV
responses, the order of music intensity was randomized to each
volunteer. In this context, we discarded the influence of this
mechanism on cardiac autonomic responses induced by musical
auditory stimulation. However, it does not rule out the influence of
habituation. Indeed, Iwanaga et al26 evaluated HRV during exposure
to repetitive musical auditory stimulation with excitatory and
sedative music. The authors observed that in the second session of
music exposure, the LF index in normalized units and the LF/HF ratio
increased, whereas no significant change in the HF index was
observed, indicating that HRV reduced after repetitive exposure to
music. In this regard, we believe that the habituation of cardiac
autonomic responses may have influenced our findings.

The cardiac autonomic responses found in our investigation are
supported by previous studies that showed physiological



J.A.T. do Amaral et al. / Journal of Traditional and Complementary Medicine 6 (2016) 23e2828
mechanisms to explain it. The brain and brain stem process audi-
tory27 and cardiovascular information.28,29 Histaminergic H3 re-
ceptors in the suprachiasmatic nucleus of the hypothalamus were
also reported to be involved in sympathetic and parasympathetic
responses induced by relaxant music.18 Musicians were exposed to
self-selected piece of music that induced intense pleasant
emotional responses and increases in regional cerebral blood flow
in the left ventral striatum and dorsomedial midbrain and re-
ductions in the right amygdala and left hippocampus/amygdala,
suggesting that music recruits neural mechanisms of recom-
pense.24,30 In addition, a recent study reported that dopamine
release in the right caudate and the right nucleus accumbens, brain
areas related to reward mechanisms,31 increased during exposure
to self-selected pleasurable music.32 In this circumstance, an
important question to be raised is the style of music used by the
authors because each study used different music. Thus, we must be
careful when interpreting data.

To avoid sex-dependent effects on cardiac autonomic responses
elicited by music, we investigated only women in this study. The
literature reported contradictory data regarding cardiovascular and
physiological responses between men and women. Cardiac auto-
nomic responses induced by auditory stimulation were suggested
to be dependent on sex regarding experience and emotional
expression.33Womenwere observed to have more intense stressful
responses induced by auditory stimulation compared with men. It
was also indicated that sex-based differences in psychophysiolog-
ical responses to auditory stimulation are strongly influenced by
hormonal status.19 Nonetheless, there is a lack of this information
in the literature studies that investigated differences between
women and men concerning the cardiac autonomic responses to
musical auditory stimulation. Furthermore, the menstrual cycle
was also indicated to affect baseline nonlinear properties of HRV.34

To exclude the interference of the follicular and luteal phases of the
menstrual cycle on cardiac autonomic regulation, we did not
evaluate volunteers on 10e15 days and 20e25 days after the 1st day
of the menstrual cycle.

5. Conclusion

Auditory stimulation with baroque and heavy-metal music
styles at lower intensities acutely decreased global modulation of
HR, whereas only heavy metal reduced HRV at higher intensities.
We suggest that the equivalent sound level range in the music
selected in our study presents significant effect on cardiac auto-
nomic regulation.

Conflicts of interest

All contributing authors declare no conflicts of interest.

References

1. Phipps MA, Carroll DL, Tsiantoulas A. Music as a therapeutic intervention on an
inpatient neuroscience unit. Complement Ther Clin Pract. 2010;16:138e142.

2. Lin LC, Lee MW, Wei RC, Mok HK, Yang RC. Mozart K.448 listening decreased
seizure recurrence and epileptiform discharges in children with first unpro-
voked seizures: a randomized controlled study. BMC Complement Altern Med.
2014;14:17.

3. Chuang CY, Han WR, Li PC, Young ST. Effects of music therapy on subjective
sensations and heart rate variability in treated cancer survivors: a pilot study.
Complement Ther Med. 2010;18:224e226.

4. Valenti VE, Guida HL, Frizzo AC, Cardoso AC, Vanderlei LC, Abreu LC. Auditory
stimulation and cardiac autonomic regulation. Clinics (Sao Paulo). 2012;67:
955e958.

5. Heart rate variability: standards of measurement, physiological interpretation
and clinical use. Task Force of the European Society of Cardiology and the North
American Society of Pacing and Electrophysiology. Circulation. 1996;93:
1043e1065.
6. Vanderlei LC, Pastre CM, Hoshi RA, Carvalho TD, Godoy MF. Basic notions of
heart rate variability and its clinical applicability. Rev Bras Cir Cardiovasc.
2009;24:205e217.

7. Okada K, Kurita A, Takase B, et al. Effects of music therapy on autonomic
nervous system activity, incidence of heart failure events, and plasma cytokine
and catecholamine levels in elderly patients with cerebrovascular disease and
dementia. Int Heart J. 2009;50:95e110.

8. Lee GS, Chen ML, Wang GY. Evoked response of heart rate variability using
short-duration white noise. Auton Neurosci. 2010;155:94e97.

9. de Castro BC, Guida HL, Roque AL, et al. Previous exposure to musical auditory
stimulation immediately influences the cardiac autonomic responses to the
postural change maneuver in women. Int Arch Med. 2013;6:32.

10. Corrêa PR, Catai AM, Takakura IT, Machado MN, Godoy MF. Heart rate vari-
ability and pulmonary infections after myocardial revascularization. Arq Bras
Cardiol. 2010;95:448e456 [Article in Multiple languages].

11. Tarvainen MP, Niskanen J-P, Lipponen JA, Ranta-aho PO, Karjalainen PA. Kubios
HRV e A software for advanced heart rate variability analysis. In: van der
Sloten J, Verdonck P, Nyssen M, Haueisen J, eds. 4th European Conference of the
International Federation for Medical and Biological Engineering. Berlin, Germany:
Springer; 2008:1022e1025.

12. Valenti VE, Guida HL, Monteiro CBM, et al. Relationship between cardiac auto-
nomic regulation and auditory mechanisms: importance for growth and devel-
opment. J Hum Growth Dev. 2013;23:94e98.

13. Abreu LC. Heart rate variability as a functional marker of development. J Hum
Growth Dev. 2012;22:279e281.

14. Roque AL, Valenti VE, Guida HL, et al. The effects of different styles of musical
auditory stimulation on cardiac autonomic regulation in healthy women. Noise
Health. 2013;15:281e287.

15. Roque AL, Valenti VE, Guida HL, et al. The effects of auditory stimulation with
music on heart rate variability in healthy women. Clinics (Sao Paulo). 2013;68:
960e967.

16. Welter KJ. Johann Pachelbel: Organist, Teacher, Composer, A Critical Reexamina-
tion of His Life, Works, and Historical Significance [dissertation]. Cambridge, MA:
Harvard University; 1998.

17. Nakamura T, Tanida M, Niijima A, Nagai K. Effect of auditory stimulation on
parasympathetic nerve activity in urethane-anesthetized rats. In Vivo. 2009;23:
415e419.

18. Nakamura T, Tanida M, Niijima A, Hibino H, Shen J, Nagai K. Auditory stimu-
lation affects renal sympathetic nerve activity and blood pressure in rats.
Neurosci Lett. 2007;416:107e112.

19. Nater UM, Abbruzzese E, Krebs M, Ehlert U. Sex differences in emotional and
psychophysiological responses to musical stimuli. Int J Psychophysiol. 2006;62:
300e308.

20. Turpin G, Siddle DA. Cardiac and forearm plethysmographic responses to high
intensity auditory stimulation. Biol Psychol. 1978;6:267e281.

21. Eder DN, ElamM,Wallin BG. Sympathetic nerve and cardiovascular responses to
auditory startle and prepulse inhibition. Int J Psychophysiol. 2009;71:149e155.

22. Daee S, Wilding JM. Effects of high intensity white noise on short-term
memory for position in a list and sequence. Br J Psychol. 1977;68:335e349.

23. Burns JL, Labb�e E, Arke B, et al. The effects of different types of music on
perceived and physiological measures of stress. J Music Ther. 2002;39:
101e116.

24. Blood AJ, Zatorre RJ. Intensely pleasurable responses to music correlate with
activity in brain regions implicated in reward and emotion. Proc Natl Acad Sci
USA. 2001;98:11818e11823.

25. Zeki Al Hazzouri A, Haan MN, Deng Y, Neuhaus J, Yaffe K. Reduced heart rate
variability is associated with worse cognitive performance in elderly Mexican
Americans. Hypertension. 2014;63:181e187.

26. Iwanaga M, Kobayashi A, Kawasaki C. Heart rate variability with repetitive
exposure to music. Biol Psychol. 2005;70:61e66.

27. Schecklmann M, Landgrebe M, Kleinjung T, et al. State- and trait-related al-
terations of motor cortex excitability in tinnitus patients. PLoS One. 2014;9:
e85015.

28. Valenti VE, Abreu LC, Sato MA, Ferreira CATZ. (3-amino-1,2,4-triazole) injected
into the fourth cerebral ventricle influences the Bezold-Jarisch reflex in
conscious rats. Clinics (Sao Paulo). 2010;65:1339e1343.

29. Valenti VE, De Abreu LC, Sato MA, Fonseca FL, Riera AR, Ferreira C. Catalase
inhibition into the fourth cerebral ventricle affects bradycardic para-
sympathetic response to increase in arterial pressure without changing the
baroreflex. J Integr Neurosci. 2011;10:1e14.

30. Salimpoor VN, van den Bosch I, Kovacevic N, McIntosh AR, Dagher A, Zatorre RJ.
Interactions between the nucleus accumbens and auditory cortices predict
music reward value. Science. 2013;340:216e219.

31. Leite-Morris KA, Kobrin KL, Guy MD, Young AJ, Heinrichs SC, Kaplan GB.
Extinction of opiate reward reduces dendritic arborization and c-Fos expres-
sion in the nucleus accumbens core. Behav Brain Res. 2014;263:51e59.

32. Salimpoor VN, Benovoy M, Larcher K, Dagher A, Zatorre RJ. Anatomically
distinct dopamine release during anticipation and experience of peak emotion
to music. Nat Neurosci. 2011;14:257e262.

33. Kring AM, Gordon AH. Sex differences in emotion: expression, experience, and
physiology. J Pers Soc Psychol. 1998;74:686e703.

34. Bai X, Li J, Zhou L, Li X. Influence of the menstrual cycle on nonlinear properties
of heart rate variability in young women. Am J Physiol Heart Circ Physiol.
2009;297:H765eH774.

http://refhub.elsevier.com/S2225-4110(14)00046-7/sref1
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref1
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref1
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref2
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref2
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref2
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref2
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref3
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref3
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref3
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref3
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref4
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref4
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref4
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref4
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref5
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref5
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref5
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref5
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref5
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref6
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref6
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref6
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref6
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref7
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref7
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref7
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref7
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref7
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref8
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref8
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref8
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref9
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref9
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref9
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref10
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref10
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref10
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref10
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref10
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref11
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref11
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref11
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref11
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref11
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref11
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref11
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref12
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref12
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref12
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref12
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref13
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref13
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref13
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref14
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref14
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref14
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref14
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref15
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref15
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref15
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref15
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref16
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref16
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref16
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref17
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref17
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref17
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref17
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref18
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref18
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref18
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref18
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref19
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref19
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref19
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref19
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref20
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref20
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref20
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref21
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref21
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref21
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref22
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref22
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref22
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref23
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref23
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref23
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref23
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref23
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref24
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref24
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref24
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref24
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref25
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref25
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref25
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref25
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref26
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref26
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref26
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref27
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref27
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref27
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref28
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref28
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref28
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref28
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref29
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref29
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref29
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref29
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref29
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref30
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref30
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref30
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref30
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref31
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref31
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref31
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref31
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref32
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref32
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref32
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref32
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref33
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref33
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref33
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref34
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref34
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref34
http://refhub.elsevier.com/S2225-4110(14)00046-7/sref34

	Effects of auditory stimulation with music of different intensities on heart period
	1. Introduction
	2. Methods
	2.1. Study population
	2.2. Noninclusion criteria
	2.3. Initial evaluation
	2.4. Measurement of the auditory stimulation
	2.5. HRV analysis
	2.6. Linear indices of HRV
	2.7. Protocol
	2.8. Statistical analysis

	3. Results
	4. Discussion
	5. Conclusion
	Conflicts of interest
	References