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IB Biology Lab Cover Sheet
Title: Heart Rate Design Lab
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D_____DCP ______ CE_______
DESIGN
ASPECT 1: DEFINING THE PROBLEM AND SELECTING VARIABLES
Background Information:
The heart is a vital organ made of cardiac muscle that pumps blood throughout the body.
Heart rate is associated with the contraction of the different chambers of the heart, and is
considered myogenic. As a result, the heart beat is controlled independently of the central
nervous system and is instead controlled by the pacemaker, also known as the Sino arterial
node. The node sends signals through nerves in the heart to other nodes such as the AV or
atrio-ventricular node and these result in the contraction of the chambers (Copeland, 1991).
Heart rate is the number of heart beats per unit of time, typically expressed in beats per minute
or bpm. The average heart rate at rest under normal conditions of adolescents and adults is 63.3
bpm ± 13.1 bpm, with variability of 3.2 bpm ± 2.1 (Leschka, 2006). Other factors also have an
influence on the heart beat and heart rate such as the medulla of the brain of the hormone
adrenaline.
External stimuli or external factors also result in alterations of the heart rate. These
include physical and emotional factors. One type of external stimuli that is shown to have
effects on the heart rate is sound, specifically music. Music is currently being considered to be
used as therapy for coronary conditions as well as on anxiety (Smolen et al, 2002). In addition,
music is widely prevalent in the lives of adolescents. Teenagers in this day are age are exposed
to music on a regular basis and a majority of adolescents living in the United States own mp3
or I-Pods (Epperson, 2011).
Sound has been shown to have effects on the heart rate. The average volume at which
adolescents listen to music is 80 decibels which is approximately 80% volume on a music
player using standard headphones (Epperson, 2011). Increasing volume has been shown to
increase the heart rate, and decreasing volume has been shown to lower the heart rate (Okamoto,
2011). In addition, studies have been conducted that investigate different genres of music and
their effects on heart rate as well as other heart application such as blood pressure.
Problem question:
What is the effect of different genres of music on the heart rate (bpm) of adolescents?
Hypothesis with Explanation:
If a subject is exposed to different genres of music for equal amounts of time and his/her
heart rate is measured in bpm, then the subject’s heart rate will show the greatest increase while
listening to techno music and will show the greatest decrease while listening to classical music.
According to a study performed in Japan, hearing classical music results in a small variance of
Mayer Wave which results in the lowering of the heart rate (Mamoru, 1998). This is because the
sympathetic nerve is suppressed by the sound of classical music. In addition, rapid changes in
volume and fast paced tempos cause the heart rate to increase (Epperson, 2011). These elements
are what techno songs are composed of, and therefore an increased heart rate can be predicted
upon listening to them.
Variables:
Dependent:
The dependent variable is the heart rate of the subject measured in beats per minute
(bpm±1.0bpm). This measurement will be taken by placing the index and middle finger on the
wrist of the subject who has been exposed to different genres of music. The music will be played
for three minutes and the heart rate will be measured by taking the pulse of the subject for one
minute (while the subject continues to listen to the music). The quantitative data will be the heart
rate in beats per minute of the subject for each genre of music. The qualitative will include
changes in facial expression, skin temperature, skin color, and any detected involuntary
movement.
Independent:
The independent variable is the genre of music the subject is exposed to while their heart
rate is being measured. The levels of the independent variable will include five different genres
of music. These will include classical music, pop music, rock music, techno or dubstep music,
and country music. These genres vary in style and tempo or speed.
ASPECT 2: CONTROLLING VARIABLES
Controlling Variables:
Table 1. Controlled variables kept constant- reasoning and method
CONTROLLED
WHY it must be controlled
HOW it is controlled
VARIABLES
1.Ambient Conditions
(Location of Experiment)
The location must be controlled and
kept the same in the experiment because
altering the environment would add
additional factors to the experiment.
Differences in temperature, lighting, or
background noise could have an impact
on the heart rate of the subject.
This variable is controlled by
conducting the experiment in
the same location for each
trial. The subjects will be
seated in the same chair in the
same class room for all trials.
The experiment will be
conducted on the same day in
order to ensure that ambient
conditions are identical.
2. Amount of Time the
Subject is Exposed to the
Music
If the amount of time the subject is
exposed to the different types of music
is inconsistent, the results may be
skewed. If the subject is exposed to one
genre for a shorter period of time than
others, the effects of the type of music
might not be present. If the subject is
exposed to one genre for a longer period
of time than others, the body may
adjust to the music and restore its
average heart rate
This variable is controlled by
ensuring the subject is exposed
to each genre of music for the
same amount of time before
the heart rate measurement is
taken. The subject will be
exposed to each genre of music
for three minutes before the
heart rate is measured.
3. The Amount of Time in
Between the Listening of
Each Genre of Music
The amount of time in between each
listening is important because the
subject needs time in order to restore
their average heart rate. If the time
between each genre listening differs, the
results could be altered. If the time
between trials is too short between two
listenings, the effects of the previous
genre could still be present.
This variable will be controlled
by ensuring that there is a one
minute time window between
each listening. The second
song will begin playing after
one minute has elapsed from
the conclusion of the heart rate
reading of the first song.
4. The Position of the
Subject While Exposed to
the Music
The position of a person could
potentially have an impact on the heart
rate of the person. Standing and sitting
has different effects on the nervous
system and the contact of feeling a chair
versus having just contact with the
floor during standing could influence
heart rate.
The position of the subject will
be constant throughout all
trials. The subject will be
seated in a chair in an upright
position with his/her back
against the back of the chair
with their feet planted firmly
on the ground throughout the
duration of the experiment.
5. The Volume at Which the
Music is Administered
Different volumes of sound have
different effects on the heart rate. If the
volume is not consistent, the subject’s
heart rate would be affected not only by
the genre of music, but also by the
volume of the sound.
The volume of the ear pieces
placed into the ears of the
subject will be kept constant
throughout all trials and
genres. The volume will be
kept at 80% of the maximum
volume allowed by the mp3
player or I-Pod.
Experimental Control: The experimental control is the subject when he/she is not listening to
any music genre. This means the recorded pulse rate is when no music is being played. The
experimental variables do not affect this control. It can be used as a standard of comparison
against other trials with the different genres of music.
ASPECT 3: DEVELOPING A METHOD FOR COLLECTION OF DATA
Apparatus and Materials: The materials needed are a graph to record data, an mp3 or I-Pod
music player with five preloaded songs of the classical, pop, rock, techno, and country genre, a
set of standard headphones, five different adolescent subjects, a chair, and a stop watch (time±
0.01sec).
Figure 1. Picture Representing
Radial Pulse Taking procedure
Figure 2. Diagram Showing Subject on
Chair with Headphones Listening to I-Pod
player
Procedure:
Note: All data and/or observations should be noted on a data table.
Sampling: Subjects for this experiment are to be chosen at random from the adolescent range of
12 -17 years old. The subjects will include a variety of ethnicities and will be of both male and
female.
Safety Precaution: Those with medical conditions or heart medical problems should consider the
consequences of participating in this experiment. Those will hearing conditions or problems
should not participate in this activity.
1. Allow the subject to sit in the chair in an upright position, ensuring that his/her back is
against the backing of the chair and his/her feet are firmly planted in the ground.
2. Place headphones in the subject’s two ears, but do not play any music. This is to ensure
that the act of wearing headphones is not an additional factor.
3. Conduct the first trial for the experimental control.
a. Allow the subject to sit in the chair for three minutes without the addition of
music.
b. During the three minute time interval, find the radial pulse of the subject by
bending the subject’s elbow 90° while supporting their lower arm on the arm of
the chair. Make sure that the wrist is facing down in order to fully expose the
radial artery. Place the tips of your index and middle fingers onto the wrist of the
subject’s right hand underneath the thumb, and feel for a pulse. Once a pulse is
obtained, note the correct spot.
c. After three minutes have elapsed, measure the heart rate of the subject in beats per
minute. In order to do this begin the stop watch after the first pulse is felt. Count
the number of pulses felt until the stop watch reads 60 seconds ±.01 seconds.
Record this number in the data table as quantitative data.
4. Allow the subject one minute of silence before continuing with the rest of the trials.
5. Conduct the trials involving the different levels of the independent variable.
a. Set the volume on the I-Pod to 80% or 80 decibels.
b. After one minute of silence since the first pulse reading has elapsed, begin playing
the selected classical piece of music. (Ensure that the I-Pod is set on repeat in case
the song is too short. If this step is forgotten, the song may switch and the trial
will not be valid for use.
c. Allow the subject to listen to the song for three minutes on a constant volume.
d. During the three minute time interval, find the radial pulse of the subject by
bending the subject’s elbow 90° while supporting their lower arm on the arm of
the chair. Make sure that the wrist is facing down in order to fully expose the
radial artery. Place the tips of your index and middle fingers onto the wrist of the
subject’s right hand underneath the thumb, and feel for a pulse. Once a pulse is
obtained, note the correct spot.
e. As the subject listens to the music, note changes in facial expression, skin
temperature, skin color (paleness or redness), and involuntary movement as
qualitative data.
f. After three minutes have elapsed, measure the heart rate of the subject in beats per
minute. In order to do this begin the stop watch after the first pulse is felt. Count
the number of pulses felt until the stop watch reads 60 seconds ±.01 seconds.
Record this number in the data table as quantitative data.
g. Allow the subject one minute of silence before continuing with the rest of the
trials.
h. Repeats steps 5a- 5g for all genres of music (rock, pop, techno, and country).
6. Repeat steps 1-5 three additional times for each of the five different subjects.
7. Calculate the average for each subject and the respective genres of music is order to make
a representation of the data.
8. Measure the percent change in the pulse comparing the experimental control and all
genres of music bpm in order to calculate the effect of the intensity of physical exertion
on the heart rate.
9. Conduct an ANOVA or analysis of variance test to compare the means of the control and
levels of independent variable in order to see if results are statistically significant.
10. Pooling data was done to ensure collection of significant, relevant data.
DATA COLLECTION AND PROCESSING
ASPECT 1: RECORDING RAW DATA
Qualitative:
During this experimental procedure, I noticed various qualitative observations. Each
genre of music seemed to have a different effect on the subjects. Some effects were subtle, while
others were more noticeable. No changes in the skin color or body temperature were noted.
However, slight movements were present. During the classical and country listenings, subjects
made subtle swaying movements and closed their eyes. During the pop music, the head swaying
became more “upbeat” and the subjects smiled while their eyes were open. The rock genre and
techno genres had similar movements and expression as the pop music.
Quantitative:
Table 2. Heart rates (bpm) of five subjects during resting, classical, pop, rock, techno, and
country listenings for three trials
Resting
Classical
Pop
Rock
Techno
Country
Subjects Trial (bpm± 1.0)
(bpm± 1.0) (bpm± 1.0) (bpm± 1.0) (bpm± 1.0) (bpm± 1.0)
Subject 1
Subject 2
Subject 3
Subject 4
Subject 5
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
64
64
62
67
64
66
56
54
62
68
70
72
64
66
62
60
62
58
64
60
63
52
51
54
58
62
66
59
62
57
76
72
76
70
68
73
62
60
69
72
74
75
71
74
69
72
66
70
76
74
77
64
63
72
64
67
74
70
73
68
74
76
78
70
68
72
66
66
75
76
79
77
73
74
73
62
60
58
60
62
64
60
52
58
56
62
68
60
63
56
ASPECT 2: PROCESSING RAW DATA
Explanation of Calculations:
Mean
I conducted the arithmetic mean of the different bpm values for resting and the five genres of
music (classical, pop, rock, techno, and country) for each of the five subjects. This statistic
allowed me to observe the average heart rate of each subject under the influence of the different
music genres. Through this analysis, I was able to juxtapose the data and compare the differences
in the bpm for each music genre. It gave me the ability to determine if a certain genre caused a
larger average bpm for the subject and how it changed based on the intensity of the genre.
Range
I conducted the range of bpm of all three trials for each type of exercise. This statistic allowed
me to identify the difference between the maximum value and the minimum value for bpm
during each music listening. It gave me the ability to determine the dispersion of my data for
each different genre of music. Due to its small number, this value showed me that my average
bpm for each exercise was overall consistent, and did not fluctuate greatly during the three trials.
Standard Deviation
I conducted the standard deviation of heart rate bpm from all three trials for each genre of music
conducted. This statistic allowed me to obtain a more detailed and accurate estimate of the
dispersion in the data values because one outlier can greatly exaggerate the data in the range,
therefore making it inaccurate. The standard deviation showed me the relation of the bpm for all
three trials to its mean value. Since it was a small value, it showed me that the bpm levels stayed
mainly constant throughout the trials with a small dispersion of data.
Percent Difference
I conducted a percent change in order to determine the change in my bpm values between each
genre of music and resting. By doing so, I analyzed by how much of a difference (bpm) value
there was for each genre of music compared to resting. This was done to see if there was a
significant increase or decrease in the bpm values between the genres of music and resting.
Sample Calculations:
Table 5. Comparison between of all five runners combined for each genre of music using
ANOVA (Analysis of Variance) Test
Genre
Subject
ANOVA p-value
All
Combined (5)
.461
Null hypothesis: There were no differences in the mean bpm value as a result of different genres
of music.
Alternative hypothesis: There was a difference in the mean bpm value a result different genres of
music.
ANOVA
Using Microsoft Excel, a One-way Analysis of Variance (ANOVA) test was conducted. This test
was used to determine if there was a statistically significant difference in the bpm values as a
result of exposure to different genres of music (classical, pop, rock, techno, and country).
According to the test, if the calculated probability were less than .05, the probability of selecting
the alternative hypothesis when the null hypothesis should really be supported is low and that the
differences in the bpm values were due more than just chance. This would indicate that there
was a statistical difference in average heart rates as a result of different genres of music.
Average of rest trials (bpm): (Trial 1 + Trial 2 + Trial 3)/3 = (64 bpm + 64 bpm + 62 bpm)/3 =
63.3 bpm
Range of rest trials (bpm): Largest value – Smallest value = 64.0bpm - 62.0bpm = 2bpm
Standard Deviation of rest trials: Use Excel, insert all values of resting bpm for all three trials
into “Number 1” space, then click Ok.
One Way A-NOVA of resting, and five music genres = Use Excel and the data analysis tool
pack; plug in all bpm values for resting, classical, pop, rock, techno, and country into “data
input.” Make sure that the selected input data is arranged in columns according to the genre of
music. Select “column” and input 0.05 for “alpha.” Click Ok.
Percent Change of resting to classical= Use Excel, ABS (second value-first value)/first value
= ABS (59.2bpm-64.1bpm)/64.1bpm = -7.6%
Processed Data:
Table 3. Average heart rate of five subjects (bpm) and average data dispersion for each
genre of music
Genre of
Music
Average (bpm)
Range (bpm)
Standard Deviation
Subject 1
Resting
Classical
Pop
Rock
Techno
Country
63.3
60.0
74.7
69.3
76.0
60.0
2.0
4.0
4.0
6.0
4.0
4.0
1.2
2.0
2.3
3.1
2.0
2.0
Subject 2
Resting
Classical
Pop
Rock
Techno
Country
65.7
62.3
70.3
75.7
70.0
62.0
3.0
4.0
5.0
3.0
4.0
4.0
1.5
2.1
2.5
1.5
2.0
2.0
Subject 3
Resting
Classical
Pop
Rock
Techno
Country
57.3
52.3
63.7
66.3
69.0
56.7
8.0
3.0
9.0
9.0
9.0
8.0
4.2
1.5
4.7
4.9
5.2
6.0
Subject 4
Resting
Classical
Pop
Rock
Techno
Country
70.0
62.0
73.7
68.3
77.3
62.0
4.0
8.0
3.0
10.0
3.0
12.0
2.0
4.0
1.5
5.1
1.5
6.0
Subject 5
Resting
Classical
Pop
Rock
Techno
Country
64.0
59.3
71.3
70.3
73.3
59.7
4.0
5.0
5.0
5.0
1.0
7.0
2.0
2.5
2.5
2.5
0.6
3.5
Subject
Table 4. Total average bpm of all five subjects combined, average data dispersion for each
genre, and comparison of average bpm of genres and resting using percent difference
Subject
Music
Genre
Total Average
(bpm)
Total Range
(bpm)
Standard
Deviation
Percent Difference from
Resting
Combined (5)
Resting
Classical
Pop
Rock
Techno
Country
64.1
59.2
70.7
70.0
73.1
60.1
18.0
15.0
16.0
14.0
13.0
16.0
4.7
4.3
4.7
4.5
4.1
3.8
0.0
-7.6
10.4
9.3
14.2
-6.2
ASPECT 3: PRESENTING PROCESSED DATA
90.0
80.0
Average Beats Per Minute
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
Resting
Classical
Pop
Rock
Techno
Country
Genre of Music
Figure 3. Total average heart beats per minute (bpm) for all five subjects during each type
of music genre listening and vertical bars represent standard deviation
20.0
Percent Difference from Resting
15.0
10.0
5.0
0.0
Resting
Classical
Pop
Rock
Techno
Country
-5.0
-10.0
Genre of Music
Figure 4. Percent difference from resting for five subjects combined for each genre of
music
Conclusion and Evaluation
ASPECT 1: CONCLUDING
The results supported my initial hypothesis; however, they were not statistically
significant. Initially I hypothesized that classical music would result in a lowering of the heart
rate while techno music would have the most influence on raising the heart rate. According to
my results, the percent difference between resting and classical music was -7.6% and the percent
difference between resting and techno music was 14.2%, supporting my hypothesis. Country
music also lowered the average heart rate by a lower -6.2%, while pop and rock music heighted
the heart rate by 10.4% and 9.3% respectively. The more upbeat songs such as the pop, rock, and
techno appeared to have increased the heart rates of the subjects as predicted, and the slower
more relaxed songs such as the classical and country lowered the heart rates.
Overall, the data collected was not statistically significant. Since the calculated ANOVA
probability value was .416 and greater than .05 was a large amount, the results were statistically
insignificant. According to the test, the alternative hypothesis was selected and thus, the mean
bpm values or heart rates of the five subjects were not affected by the different genres of music.
Although the percent difference indicated variation, it was not high enough to be considered
significant. Therefore, the hypothesis was actually not fully supported.
This experiment can be expanded to possibly aid in the development of new therapeutic
methods based for cardiac conditions based on music. It can also be used to help aid in the
stressful lives of teenagers, often resulting in higher-than-normal heart rates (Smolen et al, 2002).
The results of my study, although not statistically significant support the findings of other
scientists researching the field. Increases in systolic and diastolic pressures during exposure to
steady noise and music with high intensity peaks are present (Epperson, 2011). This would
account for genres of music such as techno that have a consistent beat and high peaks of volume.
the opposite can be observed for classical music that constantly changes in rhythm and lacks
high peaks of volume.
ASPECT 2: EVALUATING PROCEDURE
Systematic Error
The file for each song may have been set at a different initial volume. Although the music
player’s volume was kept constant, the original’s file volume may have had an influence on how
loud the music was.
Human Error
The act of measuring may have posed uncertainty during the experiment. In order to calculate the
beats per minute of each subject after exercise, I counted his/her pulse for a total of one minute.
It is possible that I may have miscounted certain times or missed certain heart beats, which
would have made the bpm values slightly inaccurate.
A biological error could have also played a role in this experiment. After listening to the songs
for certain amounts of time, the subject’s heart rate could have been restored back to normal.
This would have varied our bpm data because different subjects take different amounts of time
for their bodies to return to normal maintenance in which they lower/higher their heart rate to
adjust and regain homeostasis.
Limitations
Some limitations of this experiment include its ability to be generalized for the “real world” and
the majority of the population. This is because there are many different types of music genres
that could potentially affect heart rate. The experiment was limited to only five genres of music
that are deemed popular. In addition, only one song was chosen to represent each music genre,
for a total of five songs. Each music genre can be further sub divided into different categories,
allowing there to be a range of music within each genre. For example, in the classical genre there
are waltzes and symphonies, and both produce completely different sounds. Some classical
pieces may be upbeat and have a fast tempo while others may be slower. This variation and song
selection process is flawed because only one song is not sufficient to represent an entire genre.
Another limitation may deal with the chosen subjects. Although they were varied, each
individual could have potentially had an impact on the collected data. The subjects were not
surveyed. Some of them may have a tendency to listen to specific genres of music on a daily
basis thus making them liable to not show a difference in heart rate. For example, a person who
listens to pop music every day may show no difference in the heart rate compared to rest because
his/her body is accustomed to the genre.
ASPECT 3: IMPROVING THE INVESTIGATION
Improvements
There are few improvements that could be made in this investigation which would further
modify the procedure and generate more accurate results.
A heart rate monitor can be used, which would be connected to the subject while he/she is
listening to each genre of music in order to measure the precise heart beats per minute the actual
genre has on the runner at that time. This would also eliminate human error.
A stethoscope could be used to measure the runner’s heart beat. This will allow hearing of clear
concise heart beats which can be accurately measured as compared to slight pulses felt on one’s
finger through the neck. By measuring with a stethoscope, the heart beats per minute can be
accurately heard and measured without missing any heart beats.
The song selection process could be improved by selecting more than one song per genre. A total
of two or three songs per genre would make the results more accurate. In addition, a different
approach could be taken. Instead of using song genres as the independent variable, the song
tempo could be used and varied. This would eliminate the issue of genres being too vague.
In order to improve the overall ability to account for the major population, the subjects tested
during the experiment could have varied in age, and surveyed to see which type of music they
listen to most often. By measuring subjects of all different conditions, the general effect of music
genres can be measured that accounts for the whole population, not just a small sample of certain
people of a certain age. By measuring only a small sample, one only collects data that pertains to
people of that aptitude, ignoring others of different situations and possible outcomes. It becomes
an inaccurate conclusion that is not proved to be valid for all humans.
References and Citation
Broadened Population-Level Frequency Tuning in Human Auditory Cortex of Portable Music
Player Users. (2011, March). National Institute for Physiological Sciences.
Copeland, & Franks. (1991, March). Effects of types and intensities of background music on
treadmill endurance. J Sports Med Phys Fitness, 100-103.
Epperson. (2011). Music Effects the Cardiovascular System. American Heart Association.
Leschka, S., Wildermuth, S., Boehm, T., & Desbiolles, L. (2006, November). Noninvasive
Coronary Angiography with 64-Section CT: Effect of Average Heart Rate and Heart Rate
Variability on Image Quality. Radiology , 241, 378-385.
Mamoru, U., & Kaoru, H. (1998). Influence of music on heart rate variability and comfort: A
consideration through comparison of music and noise. Journal of human ergology , 27,
30-38 .
Smolen, D., Topp, R., & Singer, L. (2002, August). The effect of self-selected music during
colonoscopy on anxiety, heart rate, and blood pressure. Applied Nursing Research, 15(3),
126-136.