leeds rising independent science project...

Leeds Rising

Independent Science Project 2015

Experimental Research Study: Hearing and Reaction Time in the Game of Squash Abstract

This project examines how impaired hearing affects a squash player’s reaction time and performance. I will take five experienced squash players and measure using HD video recording their average reaction time to initiate racket movement and/or directional body movement after a “straight shot” and “boast shot,” which includes a side wall, is played. The boast shot, as shown in the diagram below, will be hit by player 2 such that the ball’s point of contact with a side wall is approximately horizontal to player 1 and therefore not yet visible to Player 1 looking directly forward. The straight shot will be aimed in between the player and the side wall, attempting to further isolate the variability of sound in the experiment and making sight more constant throughout the trials. I will then carry out the same experiment with each player wearing ear muffs and headphones emitting white noise to impair their hearing. Preliminary work in testing showed that wearing ear muffs that are open and do not impair hearing does not itself affect reaction time and that hearing impairment slightly slows reaction time in directional movement.

Background

For the last three years, I have served as an academic tutor and squash trainer for underprivileged and at-risk youth for Seattle Urban Squash, a local nonprofit organization committed to providing “free academic tutoring, squash training, and service learning to a select group of youth from underserved communities in the north Seattle area, with the goal of ensuring high school graduation and creating new pathways to college”. Their squash based sports development and academic development program for elementary school and middle school students, typically first or second generation immigrants, focuses on improving “confidence, study habits, discipline, work ethic, athletic skills, fitness, and positive social connections.” This past year there were approximately 40 students competing for only six available positions on the program, meaning that the process of selection was both competitive and difficult to carry out. I was involved in the multifaceted process to select participants for the team and noticed that there despite the week long tryout process, there was simply not enough raw data to evaluate or analyze a player’s current or potential ability.

My first exposure to a hearing impaired squash player was a student at Seattle Urban Squash affected by mild-moderate deafness (20 to 70 decibels of hearing) two years ago. The student sometimes wore a hearing aid in practice, while other times he did not, due to either forgetting his hearing aid at home or feeling that it was uncomfortable to play with. I observed that when this player was not hearing well that it somewhat impeded his ability to react to the ball, appearing more sluggish in his movements than in previous practices. I became curious about if this was simply a coincidence, or whether wearing his hearing aid could directly affect his squash play. I decided to investigate this further by creating an experiment to test how much, if any, difference might be detectable. I hope to learn more about hearing and sports performance as a result of this experiment by investigating an unfamiliar topic. I also hope to share potentially useful information with my local service organization to facilitate their work.

Several scientific studies have shown that human reaction time from audio input is microseconds faster than from visual input and hypothesize that hearing nerve pathways being more direct than visual nerve pathways contribute to this difference. This suggests that hearing impairment may slightly slow reaction time for some shots in squash.

An extensive study, “Motor Skill Performance and Sports Participation in Deaf Elementary School Children” (Non-Linear Periodization for General Fitness & Athletes, Steven) found decreased motor skills and sports participation among deaf students as compared to students without disabilities.

The English Deaf Squash Association appears to be the largest of various associations promoting the game of squash, including competitions and community, for hearing impaired persons. They provide information to assist teaching and playing squash for deaf persons, as well as information about use of hearing aids and cochlear implants.

Multiple studies have suggested that in tennis, a racquet sport with similarities to squash, loud grunting (exceeding 100 decibels) by a player upon hitting the ball, results in a slight percentage reduction in an opponent’s successful return of the ball and hypothesize that the loud sound reduces an opponent’s ability to process the struck ball’s speed and direction.

Purpose

To explore whether or not there is a correlation between hearing and an individual’s ability in the sport of squash. If there is a correlation, the purpose of the experiment will move towards studying how big an impact has on an individual’s play, and whether this impact is big enough to have a tangible difference by being larger than the subconscious human visual and auditory response time (thus having an impact that changed an individual’s capacity to react to a shot). What will be measured

I will measure the reaction time of the squash players. This will be done by recording how many frames on a Go-Pro camera it takes for a player to react to either a boast shot or a straight shots. These shots will be randomized to prevent players “guessing” when to react instead of reacting from impulse. By having the player with inhibited or not inhibited hearing stand in front of the player hitting the boast, the variable of hearing will be more isolated as sounds from the racket and side wall will be heard by the player with or without hearing before he/she can see the ball. How it will be measured

I will measure this reaction time by recording the trials on a Go-Pro camera. This will be done for five trials with hearing and five trials without hearing for each player. By measuring only the reaction time to the ball, the variability of hitting a boast shot or straight shot and the variability of a player’s time in running to the position will be eliminated. Thus, the reaction time will simply be to how quickly the player realizes that a shot has been played. Also, because the reaction time will be measured with the GoPro from the frame when player 1’s racket hits the ball to the frame when player 2 makes their racket movement, stopping the GoPro at the precise moment that player 2 hits the ball is not issue (as the camera will continue to record throughout the trials). This allows another human response time (a third human starting and stopping the camera, stopwatch, etc. at the exact moments when the ball collides first with player 1’s racket and later player 2’s racket) to be eliminated, thus further isolating the variable of hearing of player 2. Impact

On a broad level, exploring this correlation will improve understanding by squash trainers of developing hearing impaired squash players, including whether or not, and at what level of hearing impairment, hearing aids might be helpful. This can better justify cost of providing hearing aids.

On a local level, the results of this experiment may affect organizations, particularly Seattle Urban Squash, for its research on which students are most likely to succeed in squash. In addition, this experiment will seek to provide data in a more obscure topic on which no acknowledged findings have been published.

These findings are not meant to limit students from being able to play squash, but rather to supply data and analysis on whether or not certain factors of the human body can affect an individual’s squash play. In a milder manner, if data is found to show on how quickly an individual is able to react to certain shots, it might provide insight into the importance of avoiding potential long term damage to the hearing of a squash player, at both amateur and professional levels, and motivate use of hearing protection during potentially harmful noise level events, such as at music concerts, a common activity for youth, and motivate players to avoid exposure to very high noise levels right before a game.

Legacy

This experiment will provide information on whether impaired hearing has no correlation with an individual’s ability to play squash or that a lack of hearing damages an individual’s ability to play. For individuals with hearing aids, cochlear implants, or mild hearing damage, this information may prove useful. In the case that a lack of hearing is shown to have a negative impact on an individual’s squash play, a player who has damaged hearing might choose to shift their style of squash play to accommodate for the ear that is non-damaged. If it is shown that there is no correlation between a lack of hearing and the capacity of play, deaf and severely hearing hindered individuals may be drawn to play squash rather than other sports where hearing is a strong advantage.

Tryouts are held annually for my local community service agency, Seattle Urban Squash, to determine who should be added to the program’s limited roster. Because recruited applicants are young and have little or no previous experience playing squash, selections and cuts are made based upon predictions of an individual’s future success through several criteria. These include characteristics such as body build, height, general fitness, and current display of effort, desire and commitment. If this investigation shows a clear correlation between hearing and ability to play squash, selections may also consider factors related to hearing impairment and adaptive strategies to place students more likely to find success on the team. Resources needed: The following items will be used for this project:

• (1) squash court allowing access for multiple visits for participants in study. • (5) squash players, ideally with varying levels of expertise, each with their own:

• squash racket, • proper squash eye protection, • proper squash attire.

• (1) squash ball (plus one extra ball of same type), • (1) GoPro camera for recording video of squash play, • (1) tripod (or table) to support GoPro camera outside glass back wall during recording, • (1) computer for video playback of recorded squash play to measure frames per second and to

record data, • (1) clean set per player of ear protection capable of blocking most or all of the sound from a

squash ball strike, which can reach 105 decibels, and wall contact. This will be explored by testing for best combination of:

• (1) pair of highest rated commercially and readily available pair of ear muffs rated for 30 decibels of sound reduction over,

• cotton balls, lightly packed inside ear muffs for additional sound absorption, • (1) pair of highest rated commercially and readily available pair of compressible foam ear

plugs rated for 30 decibels of sound reduction (or (1) pair of ear bud headphones and music source, I-phone or similar)

• Water bottles and/or sport drinks Why is it credible or needed?

The information that this experiment will provide will show that either a lack of hearing has no correlation with an individual’s ability to play squash or that a lack of hearing damages an individual’s ability to play. For individuals with hearing aids, cochlear implants, or mild hearing damage, this

information may prove useful. In the case that a lack of hearing is shown to have a negative impact on an individual’s squash play, a player who has a damaged ear might choose to shift their style of squash play to accommodate for the ear that is non-damaged. If it is shown that there is no correlation between a lack of hearing and the capacity of play, deaf and severely hearing hindered individuals may be drawn to play squash rather than other sports where hearing is a strong advantage. How is it going to be used/is it usable?

The main importance of this study is for squash players with damaged hearing and for squash programs when evaluating athletes. Through collecting data on how hearing can affect an individual’s squash play, more information will be available on how individuals can set themselves up for success in the sport and whether or not they should choose the sport. However, the results should not be used by any means to deter individuals from playing squash, as the shots being tested only scratch the surface of the different skills and shots required to be a good squash player. Notes Drive shot (also called ‘rail’ shot): a shot that hits the front wall around the service line and with the first bounce just behind the service box, preferably with depth and tight to side wall. Boast shot: any shot that hits a sidewall (most common) or backwall before hitting the front wall. Attacking boast is played when you are in front of opponent. Defensive boast is played when behind opponent (primarily used from behind opponent only when straight shot is not possible)

Results and discussion Example Calculations and data collection 24 frames per second – 0.0417 seconds per frame

Noise Impairment

Right Boast 5.06-6.02 20 frames – 0.833 seconds

Left Boast 12.13-13.10 21 frames – 0.875 seconds

Right Straight 15.12-16.00 12 frames – 0.500 seconds



Right Boast 26.05-26.20 15 frames – 0.625 seconds

Left Straight 39.04-39.18 14 frames – 0.583 seconds



Left Straight 1.03.14-1.03.22 8 frames – 0.333 seconds

Left Boast 1.27.22-1.28.13 15 frames – 0.625 seconds




Right Straight 2.20.04-2.20.13 11 frames – 0.458 seconds

Right Boast 2.56.21-2.57.12 15 frames – 0.625 seconds





With Noise Impairment





Right Straight 5.22.18 – 5.23.09 15 frames – 0.625 seconds

This style of data of collecting data is then carried out for each of the five players. A simplified table is provided on the following pages.

Without Impairment

Straight shot- L

Reaction time

Boast shot- L

Reaction time

Straight shot- R

Reaction time

Boast shot- R

Reaction time

Trial 1 39.04-39.18

0.583 seconds

12.13-13.10

0.833 seconds

15.12-16.00

0.500 seconds

5.06-6.02

0.833 seconds

Trial 2 44.23-44.40

0.708 seconds

1.27.22-1.28.13

0.625 seconds

19.14-19.23

0.875 seconds

26.05-26.20

0.625 seconds

Trial 3 52.00-52.08

0.333 seconds

1.43.10-1.43.18

0.333 seconds

22.12-23.03

0.583 seconds

2.56.21-2.57.12

0.625 seconds

Trial 4 1.03.14-1.03.22

0.333 seconds

2.07.03-2.07.14

0.458 seconds

2.20.04-2.20.13

0.458 seconds

3.00.10-3.01.08

0.917 seconds

Trial 5 1.50.07-1.50.12

0.208 seconds

3.34.19-3.35.13

0.750 seconds

3.19.23-3.20.13

0.583 seconds

3.43.17-3.43.15

0.917 seconds

Average 0.433 seconds 0.600

seconds 0.600 seconds 0.738

seconds

With Impairment

Straight shot- L

Reaction time

Boast shot- L

Reaction time

Straight shot- R

Reaction time

Boast shot- R

Reaction time

Trial 1 5.00.18-5.01.08

0.583 seconds

5.34.14-5.35.12

1.00 seconds

5.22.18-5.23.09

0.625 seconds

6.53.15 6.54.10

0.792 seconds

Trial 2 5.07.06-5.08.01

0.917 seconds

5.43.16-5.44.12

0.625 seconds

6.16.03-6.16.19

0.667 seconds

7.04.09-7.05.11

1.083 seconds

Trial 3 5.11.19-5.12.09

0.583 seconds

5.54.15-5.55.06

0.625 seconds

6.20.11-6.21.04

0.708 seconds

7.30.18-7.31.10

0.666 seconds

Trial 4 5.11.02-5.11.21

0.792 seconds

6.32.18-6.33.10

0.667 seconds

7.09.17-7.10.01

0.333 seconds

7.39.23-7.40.15

0.666 seconds

Trial 5 5.56.23-5.57.16

0.708 seconds

6.48.01-6.48.21

0.833 seconds

7.16.15-7.17.10

0.792 seconds

7.46.03-7.46.21

0.750 seconds

Average 0.716 seconds

0.750 seconds

0.625 seconds

0.791 seconds

Without Impairment

Player 1 Reaction time straight (Left)

Reaction time boast (Left)

Reaction time straight (Right)

Reaction time boast (Right)

Trial 1 0.583 seconds 0.833 seconds 0.500 seconds 0.833 seconds Trial 2 0.708 seconds 0.625 seconds 0.875 seconds 0.625 seconds Trial 3 0.333 seconds 0.333 seconds 0.583 seconds 0.625 seconds Trial 4 0.333 seconds 0.458 seconds 0.458 seconds 0.917 seconds Trial 5 0.208 seconds 0.750 seconds 0.583 seconds 0.917 seconds Average 0.433 seconds 0.600 seconds 0.600 seconds 0.738 seconds





















With Impairment


























By using the averages of each shot from each player, we are left with the following table:

Analysis

In general, these results parallel the results hypothesized before the experiment. The fact that the average difference in reaction time between the 5 players was greater than or equal to 1.500 seconds for all four types of shots shows that there is a significant difference in a player’s ability to react with and without hearing. Every shot had an average difference exceeding the average human’s auditory reaction time of 0.14 seconds, but only not the shots from the left side of the court (the left straight shot and left boast shot) exceeded the mean human visual reaction time of 0.18 seconds. Since all of the players involved in the experiment, this data would suggest that each player tended to expect the ball to be played on their right side, meaning that when a left straight or left boast shot was utilized players had a longer reaction time because of the "unexpected” nature of the shot. However, the fact that impaired hearing still resulted in an average increased reaction time still acts as evidence that sound does play a significant factor in the sport of squash. A lack of sound may force a player to have to compensate for their slower reaction to shots in other ways, but because the difference is still negligible even with complete lack of hearing, slightly impaired hearing should not turn an individual away from the sport.

The other interesting finding that is shown through this data is that the type of shot (a straight shot

versus a boast shot) was not the largest determinant on the resulting reaction time. Rather, the side that the shot was played on made the largest difference on the reaction time of the shot. This can be seen by how the average difference between impaired and unimpaired hearing on the left side was 0.257 seconds and 0.231 for straight shots and boast shots, respectively. The difference of 0.026 seconds is negligible considering the inaccuracies in the setup and execution of the experiment, but is still in accord with the original idea that an individual will be able to react to a boast shot faster because of the additional sound generated when the ball hits the side wall. On the right side, however, the difference between unimpaired and impaired hearing was far smaller both for straight shots and boast shots. The average difference between straight shots and boast shots was 0.168 seconds and 0.l50 seconds, respectively. With only a difference of 0.018 seconds between these two shots, it can yet again be said that this difference is too small to appear major when considering the inaccuracies involved in the experiment.

The original hypothesis for the experiment was that boast shots would have a much larger

difference in reaction time than straight shots. This was theorized because players, generally, know a boast is being played because of the sound made from the side wall, while this additional side wall sound is nonexistent for straight shots. This difference appeared to be nonexistent in the data, as the difference between straight and boast shots was quite negligible, as previously stated. What made the largest difference was the side that the straight and boast shots were played on, as the difference between the right and left straight shots was 0.089 seconds and 0.081 seconds for the right and left boast shots. While

Reaction time straight (Left)




Unimpaired Hearing

0.395 seconds 0.540 seconds 0.507 seconds 0.632 seconds

Impaired Hearing


Average Difference


these differences are also quite small and may be attributed to inaccuracies in the experiment, there is still a trend in the differences between the two sides that is worth considering.

For instance, both the reaction times for the left straight and left boast shots were considerably

smaller than the reaction times for the same shots on the right hand side (approximately 0.100 seconds smaller for both shots). All of the players in the experiment were right handed, which would initially suggest that players should be quicker in the reflexes on the side that they traditionally play more shots on (the forehand shot, per se). However, this data of reaction time without hearing impairment seems to show otherwise. This reaction time advantage on the left side then falls away when hearing impairment is added, making the difference between the right and left hand sides less than 0.025 seconds for both sides. This might suggest that the players involved in the experiment had the same visual reaction time for the straight and boast shots on both sides, as there was only visual stimulus present when hearing was completely impaired. Thus, when considering that the shots on the left hand side had a considerably smaller reaction time difference, the data suggests that players were able to react to the auditory stimuli on their offhand side (backhand) than on their main hand side (forehand). However, because the differences between these reaction times is still quite small and could skewed by inaccuracies in data testing, it is not reasonable to conclude that this was the result found in the experiment.

Another unexpected trend that was shown throughout the data was that while the experienced

players had lower reaction times without impaired hearing, they had almost the exact same reaction time as unexperienced players with impaired hearing. Player 3 was the most experienced player out of the five, having played for 10 years or more than the other four. This is shown in the unimpaired hearing, as his average reaction time for the four shots was over 0.100 seconds shorter than the other four players. Player 2 had the second most experience, but was not too much more experienced than the players 1, 4, and 5. This is once again shown in the unimpaired data, as player 2 had an average reaction time of 0.556 seconds throughout the four different types of shots, the second lowest average (with player 3 having the lowest general average reaction time of 0.321 seconds).

While this is advantage gained through experience is predictable, the unexpected trend is found

when the general averages of the players are compared with impaired hearing. While player 3’s general average reaction time was 0.235 seconds faster with unimpaired hearing, this difference in reaction time shrank with impaired hearing to 0.023 seconds (with player 2 having a general average impaired reaction time of 0.635 seconds and player 3 having a general average impaired reaction time of 0.658 seconds). This means that despite player 2’s advantage in reaction time over player 3 with unimpaired hearing, this advantage was almost entirely eliminated (at least to the point of being quite negligible) when both player’s hearing was impaired. This would suggest that player 2 was trained to react to the auditory stimulus of the ball being hit, giving him the advantage in reaction time when hearing was available but reducing this advantage when hearing was eliminated.

However, from the data collected, the only real conclusion that can be amply backed up from the

reaction times is that impairing the hearing of the five players in the experiment resulted in an increased reaction time that was, on average, greater than the natural visual and auditory subconscious reaction time of humans. At the same time, the difference in reaction time is barely significant for players experiencing complete deafness, thus meaning that a player having slightly better hearing than their opponent by no means makes them a more competent player. Sources of Error Because of the small reaction times that were being calculated in this experiment (reaction times that were on the order of thousandths) and the difference that could be made in the final conclusions from just several more or less frames from the GoPro camera, finding precise data was crucial for arriving at

accurate results and analysis. The first major systematic source of error present in this experiment was a lack of precise technology. A GoPro is already an expensive device, but despite this it still lacked the accuracy to get each stage of measuring reaction time (the frame when the ball hit player 2’s racket and the frame when player 1 moved his/her racket) at the precise moment. Because of this, some of the reaction times may have been off by as much as just less than a whole frame (slightly smaller than 0.0417 seconds). If a camera with more than 24 FPS (the FPS of the GoPro camera) could be used instead, more accurate results could be obtained that might show the current trends in the data more clearly or show new trends. The second major source of error prevalent in the collection of the data was an inability for player 2 (myself) to play entirely consistent and accurate straight and boast shots. Because there was a variance for these shots, the resulting reaction times could have been very easily skewed simply by how I played the shot rather than from the presence of absence of sound. For example, if I played some of the right straight shots with greater pace than some of the left straight shots (as I am a right-handed player), it is possible that the player 1 in these trials would see the ball quicker, receive visual stimulus faster, and thus react earlier. This systematic error may have resulted in the trend of shots on the left side having a smaller reaction time than shots played on the right side, as discussed in the analysis section. If a ball machine had been in place of player 2, more consistent shots could have been played and more accurate trends could have been revealed in the data. The final major systematic source of error was the difficulty in finding the exact moment that player 1 reacted to the shot being played, as indicated by a sharp movement in his/her racket. Because player 2 and player 1 both sometimes the GoPro’s filming of player 1’s racket, it was difficult to find the exact frame when player 1’s racket is first moved. Unlike the previous sources of error, this source of error likely affected a few, select data points but had a large impact. This might be an explanation for some of the outlying reaction times (particularly those that were much larger than the others) and could be eliminated through positioning the camera at the front of the court instead of the back.

Works Cited Deaf-Friendly Squash Resource. England Deaf Squash Association, n.d. Web. 17 July 2015. Fleck, Steven J. "Non-Linear Periodization for General Fitness & Athletes." Journal of Human Kinetics.

Versita, Warsaw, 29 Sept. 2011. Web. 08 Aug. 2015.

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