Music Effects on Drivers' Reaction Times

by Susan Strick
January 2000

Abstract

The purpose of this research was to determine the effect of music in a car on the driver’s reaction time. Ten females between the ages of fifteen and seventeen were each tested on two different days. They were tested in a car with the music at zero, fifty, sixty-five, and ninety-five decibels. During testing they were each shown a series of road signs and they had to determine whether or not they should brake. Each subject’s times were then recorded and averaged so there was one score for each level of music. Of the ten subjects that were tested, most of them did show that the volume of the music did affect their reaction time. On average there was a .12 second difference in reaction times with music at zero decibels and ninety-five decibels. Although this difference seems quite insignificant, the time that it takes to actually react to a child running in the street or to another car running a red light for example, can actually mean the difference between life and death. Many people think that they are not affected by the volume of their music , but the truth is that as the music gets louder, it takes longer to react. In general, the majority of all drivers should keep their music between fifty and sixty-five decibels not only for hearing preservation but so that they can remain focused. Despite the fact that some drivers like to have their radio in the car quite loud, it does affect reaction times and in turn, the lives of the driver as well as others.

Problem Statement

The purpose of this research is to determine if the volume of music in the car affects a driver’s reaction time.

Research and Literature Review

Health and safety concerns need to come before preference. This is true for many things, including the volume of music while driving. As the volume of music increases in the car, many people tend to give their attention to the words or the rhythm of the music and their attention is taken away from the road and their surroundings. An obvious danger to loud music in the car is the fact that as it become increasingly louder the ability to hear emergency vehicles decreases. The Ohio State Highway Patrol strongly cautions against using headphones while driving, although there is no law against headphones or dangerously loud music. (Traffic Safety Department 209). In addition to causing decreased attention, loud music in confined spaces can cause significant, permanent hearing loss. Most hearing loss is gradual, beginning with the loss of occasional words, and long-term exposure can eventually lead to deafness. Hearing loss affects more than 28 million people in the United States and approximately 10 million of them can attribute their hearing loss to being subjected to loud noises (Cook 431).

It is hard to avoid the noise though. Noise is everywhere. There can be harmful amounts in our jobs, entertainment, recreation, neighborhood, homes, and even in our cars. More than 20 million Americans are exposed to potentially harmful noise each day (Cook 431). A majority of the causes for hearing loss can be prevented. There are many consumer products to protect hearing and there are many efforts being made to have local environmental noises controlled, including public events. The initial effects of hearing loss are the obvious ones. Being unable to hear well is an inconvenience, but most people learn to cope. On the other side of things, friends and family may become less willing to talk and repeat sentences to someone who is hard of hearing and has trouble understanding everyday conversation. Ultimately, the hearing impaired may lose friends due to their disability and may fall into a state of emotional depression. This is not a rare occurrence as many people are afflicted by gradual or sudden hearing loss. Not only can noise cause hearing loss, it may also lead to extreme emotions and behaviors as well as anti-social behavior. Many times people do not recognize that their hearing loss is the result of noise, and many times the loss is so gradual that it is hard to know that the damage did originate from prolonged exposure to noise.

Noise not only affects people the are directly responsible for it, but children and even fetuses. Noise has affected the education of children if many ways. Noise can hinder the child’s ability to develop proper language skills as well as reading development. When exposed to loud noise over time, children may already begin to show signs of hearing loss when then are just developing their language skills. For example, they may confuse similar letters and sounds and could quite possibly never learn to tell the difference between them. A study of children between grades two through five was conducted assessing their reading skills. The study concluded that the noise level in the childrens’ home was more influential to their learning than their parents’ educational background (Cook 437). Some people may think that external hazards can only affect those that are already born, but research shows information contradicting this. Loud noises have been proven to stimulate the fetus. These results have been displayed as an increase in fetal heart rate as well as increased fetal kicking later in the pregnancy. Noise can not only stimulate the unborn child but it can also do permanent damage. The fetus is not fully protected from noise and any loud sounds that it is subjected to may threaten fetal development. In addition to the full development of the baby, loud noises have been linked to low birth weights, which can be quite dangerous (Cook 435).

There are other dangers to noise around us; they are not restricted to hearing loss, complications from it, or those dangers directly involving the body. One major concern among public safety experts is the noise of the city which can obscure warning signals such as sirens causing more accidents to occur. Noise can also interfere with shouts for help in a crisis situation making rescue attempts nearly impossible (Cook 443).

While many people may not realize the long term effects of being exposed to loud noises. They also don’t realize that these hazards are not merely occupational hazards. Machinery in factories or loud concerts can obviously be damaging to hearing, but everyday noises can also be quite damaging if heard for extended periods of time. The National Institute for Occupational Safety and Health says that no worker should be exposed to sounds louder than 85 decibels for more than eight hours. After this period of time there is a danger of hearing loss. This source states that as the decibel level decreases. the time a worker can be exposed to the noise increases and vise versa. (NIOSH 2)

When listening to music , most people do not realize the noise equivalence of the volume of their music. Everyday conversation is approximately 55 decibels while the threshold of pain is about 120 decibels. A jet airplane is 150 decibels, and a rocket engine is 180 decibels (Friedhoffer 67, Gardner 74). Experts have recommended that people should not be exposed to noises louder than 85 decibels for extended periods of time, but many rock concerts ring in at 120 decibels and car radios are often nearly that loud.

Although hearing preservation is one major concern for those subjected to loud noises, the attentiveness of those who listen to music while driving is another problem. The average reaction time of most drivers is 3/4 of a second and if a car is traveling 60 mph, the car will travel an additional 66 feet before the brakes are even applied to start to slow the car (Kelley 49). With music or any other distractions, the reaction time will most likely increase causing the car to travel an even longer distance before it begins to slow. In turn, this lack of attention can cause accidents involving other cars, children, or drivers. There are many things that can turn the driver’s attention away from the road and one of those things happens to be music. Research showed that the volume of the music also affects the alertness of the driver and can cause their reaction time to increase.

Although loud noises and music can create tremendous consequences including hearing loss and depression, the consequence of diverting attention from the road to the music while driving in a car can be life threatening. The obvious answer to end self-induced hearing loss, complications from it, and increased reaction time in a car setting would be to simply turn down the music. Many Americans do not realize this and until they turn down the music, people will continue to lose their hearing and to be unsafe drivers.

Hypothesis

If the volume of the music increases, then the reaction time will also increase, causing the person to take more time to apply the brakes of the car.

Procedure

For this experiment, ten people were each tested twice in the following manner.

1. Subjects sat in 1998 Jeep Grand Cherokee Laredo in the garage. They adjusted seat to their preference and then rolled up all windows and couldn’t hear anything going on outside of the car. The car was turned on in "accessory mode" so that the lights and radio worked but the motor was not running.

 

2. They were first tested without any music playing in the car. There were five different signs to which the driver needed to react. The signs were a stop sign, railroad-crossing sign, deer crossing sign, speed limit sign, and a soccer ball. The driver was directed to stop on the stop sign, railroad crossing sign, and the soccer ball. The soccer ball symbolized a child running into the street after the ball. The speed limit sign and the deer crossing sign were used to make sure that the driver thought about if they needed to brake so that they were not automatically braking when they saw a sign.

 

3. The signs were held up in the same order each time and timed from the moment the sign was help up to the moment the brake lights came on using a stop watch. The order of the signs was stop, deer crossing, soccer ball, railroad crossing, speed limit, deer crossing, and stop sign.

 

4. After completing testing at zero decibels, each subject was tested listening to music at fifty, sixty five, and ninety-five decibels. Each subject was tested using the same song, "I Want It That Way" by the Backstreet Boys. They were tested on two different days to minimize any possible influence caused by lack of sleep, time of day, stress, or other factors that could alter their statistics.

5. The times for both days were then averaged so that there was one score per subject for each level of music. 

Experimental Design

Experimental Groups-the tests that the subject listened to the music at fifty, sixty-five and ninety-five decibels.

Controlled Group-the zero decibel/no noise group determined the reaction time for each person

Independent Variable-the volume of the music

Dependent Variable-the reaction time of each subject

Controlled Variables-stopwatch, car, signs, location, song, decibel meter, age group, gender, order of signs

Materials

 

 

1998 Jeep Grand Cherokee Laredo

stop watch

stop sign

speed limit sign

railroad crossing

deer crossing sign

soccer ball

recording of "I want it that way" by the Backstreet Boys

decibel meter 

Observations

I collected data from 10 different females between the ages of 15 and 17. Each female was tested on two different days and the scores for each subject were then averaged. Each subject’s time was then averaged with the others to get one overall average for each volume. Those averages are displayed in Table 1 below.

Each time is displayed in seconds.

 

Table 1

Graph 1 displays the data by decibel level. Graph 2 shows subjects A-E, while Graph 3 show subjects F-J. Graph 4 shows the overall average reaction time for all the subjects.

  

Conclusions and Interpretations

This research has shown that although the differences in the reaction times at each volume do not appear significant, they are. The hypothesis is supported because the overall data and material shows that, even though there are exceptions, the volume of music in a car does affect the reaction time of the driver. If the reaction time of a driver is of a second and the car is traveling at sixty miles per hour, the car will travel 66 feet before the brakes have been applied and the car begins to slow. (Kelley 49) This statistic is for of a second and many of the reaction times studied in this testing were significantly higher than that, some coming close to twice that figure.

For each subject, the results were somewhat varied. Many of the drivers were fairly consistent throughout the different volumes, and some did better with loud music than music at low levels. For some of the subjects, they did drastically worse with loud music than with no music at all. Looking at the data in its entirety, the music level does seem to be related to a driver’s reaction time. As the music level increased, the driver used an increased amount of time to apply the brakes. The middle levels of volume (fifty and sixty-five decibels) were very similar in the time it took to react. They are very similar in volume, which could account for the corresponding reaction times. One of the things that could explain the inconsistency among the drivers is the subject’s preference to the music played. Some of the subjects may like the Backstreet Boys’ "I Want It That Way" while some of the subjects may have preferred a different type of music, possibly hard rock or classical music. Another variable that couldn’t really be prevented is the type of environment the subject was used to driving in. If they have a sports car or a luxury car, the sport utility vehicle may have felt awkward for them and caused them to be less alert to their surroundings.

Overall, the data shows that for some drivers, it would be in their best interest to drive with no music, or very low music. There are very few individuals who should drive with the music at high volumes. If listened to consistently, at levels higher than 85 decibels can cause severe hearing loss. (National Institute for Occupational Safety and Health 2) Therefore, in confined spaces, cars for example, music should be at low levels in order to protect hearing and also so that there are unnecessary distractions for maximum alertness.

 

Implications for Further Research

 

There were many different things that I thought of during this test that may affect reaction time while driving. I think that it would be interesting to test if the number of people in the car affects reaction time as well as the number of distractions. If the radio was going while two or three people are talking I think that it would lengthen reaction time as opposed to just one person or no radio at all. It would also be interesting to see if the time of day affects the way a person reacts while they are driving. There are many interesting things that could be tested in a driving setting with reaction times. Some of these tests include time of day, changes in weather, number of passengers, number of other cars on the road, age of driver, ages of passengers, and the type of music that is on the radio.

 

If I were to continue this project next year I would test how the different types of music affects reaction time. This is an interesting topic for many teens because parents are constantly telling them to turn down the music while driving or turn it off all together. It would be beneficial to know if the really is reason to worry about the volume of the radio or if parents are just annoyed with they type of music teens tend to play on their radios.

 

End Notes

Cook, Allan R. Environmentally Induced Disorders Sourcebook. Detroit, Michigan: Omnigraphics, Inc., 1997

Friedhoffer, Robert. Sound. New York: Franklin Watts, 1992

Gardner, Robert. Experimenting With Sound. New York: Franklin Watts, 1991

Harfst, David L. and Jerry L. Mashaw. The Struggle for Auto Safety. C Cambridge, Massachusetts: Harvard University Press, 1990.

Kelley, Patrick. Building Safe Driving Skills. Belmont, California: Fearon-Pitman Publishers, Inc.., 1977.

Traffic Safety Department. American Automobile Association. Digest of Motor Laws. Heathrow, Florida, 1990.

United States Department of Health and Human Services. National Institute for Occupational Safety and Health. Occupational Noise Exposure. Cincinnati, Ohio: CDC, June 1998.

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