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IB Biology Lab Cover Sheet

Title: Heart Rate Design Lab

Check Required Criteria for Lab

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 VARIABLESControlling Variables:

Table 1. Controlled variables kept constant- reasoning and methodCONTROLLED

VARIABLES WHY it must be controlled HOW it is controlled

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).

Procedure:

Note: All data and/or observations should be noted on a data table.

Figure 2. Diagram Showing Subject on Chair with Headphones Listening to I-Pod

Figure 1. Picture Representing Radial Pulse Taking procedure

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

Subjects TrialResting

(bpm± 1.0)Classical

(bpm± 1.0)Pop

(bpm± 1.0)Rock

(bpm± 1.0)Techno

(bpm± 1.0)Country

(bpm± 1.0)Subject 1 1 64 60 76 72 74 62

2 64 62 72 66 76 603 62 58 76 70 78 58

Subject 2 1 67 64 70 76 70 602 64 60 68 74 68 623 66 63 73 77 72 64

Subject 3 1 56 52 62 64 66 602 54 51 60 63 66 523 62 54 69 72 75 58

Subject 4 1 68 58 72 64 76 562 70 62 74 67 79 623 72 66 75 74 77 68

Subject 5 1 64 59 71 70 73 602 66 62 74 73 74 633 62 57 69 68 73 56

ASPECT 2: PROCESSING RAW DATA

Explanation of Calculations:

MeanI 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.

RangeI 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 DeviationI 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 DifferenceI 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

Subject Genre ANOVA p-valueCombined (5) All .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.

ANOVAUsing 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

SubjectGenre of

Music Average (bpm) Range (bpm) Standard DeviationSubject 1 Resting 63.3 2.0 1.2

Classical 60.0 4.0 2.0Pop 74.7 4.0 2.3

Rock 69.3 6.0 3.1Techno 76.0 4.0 2.0Country 60.0 4.0 2.0

Subject 2 Resting 65.7 3.0 1.5Classical 62.3 4.0 2.1

Pop 70.3 5.0 2.5Rock 75.7 3.0 1.5

Techno 70.0 4.0 2.0Country 62.0 4.0 2.0

Subject 3 Resting 57.3 8.0 4.2Classical 52.3 3.0 1.5

Pop 63.7 9.0 4.7Rock 66.3 9.0 4.9

Techno 69.0 9.0 5.2Country 56.7 8.0 6.0

Subject 4 Resting 70.0 4.0 2.0Classical 62.0 8.0 4.0

Pop 73.7 3.0 1.5Rock 68.3 10.0 5.1

Techno 77.3 3.0 1.5Country 62.0 12.0 6.0

Subject 5 Resting 64.0 4.0 2.0Classical 59.3 5.0 2.5

Pop 71.3 5.0 2.5Rock 70.3 5.0 2.5

Techno 73.3 1.0 0.6Country 59.7 7.0 3.5

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 64.1 18.0 4.7 0.0Classical 59.2 15.0 4.3 -7.6

Pop 70.7 16.0 4.7 10.4Rock 70.0 14.0 4.5 9.3

Techno 73.1 13.0 4.1 14.2Country 60.1 16.0 3.8 -6.2

ASPECT 3: PRESENTING PROCESSED DATA

Resting Classical Pop Rock Techno Country0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

Genre of Music

Ave

rage

Bea

ts P

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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

Resting Classical Pop Rock Techno Country

-10.0

-5.0

0.0

5.0

10.0

15.0

20.0

Genre of Music

Perc

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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.