In Stem I we work on our independent research projects and present our ideas to one another. As well, we learn how to write proposals and formal scientific writings and understand them.

Assistive Barre Chord Playing Device for the Guitar

The objective of this project was to create a device that would make playing barre chords on the guitar more accessible. This was done by creating a motor powered device that would press down all the strings at one time, therefore playing the barre part of the chord. By playing the barre for the user, the chord as a whole was made easier to play. The device was shown to increase the users success in playing barre chords as their pitch accuracy increased and the user played the correct note more often with the device. The device makes playing barre chords easier on the guitar. In doing this, the device makes learning the guitar more accessible for everyone.

Abstract

A common technique guitarists use is a barre chord in which they press multiple strings down with one finger, which requires a great amount of grip strength, making playing the guitar not accessible for those with low grip strength. The goal of this project is to create a device that decreases the grip strength necessary to play the guitar by playing the part of the barre chord which requires a high level of grip strength for the user. First, materials were tested such as finding motor strength to find efficiency. After this, a proof-of-concept device was created, and prototypes were made and given to human participants to test. Multiple iterations were made and tested to address identified design problems. When tested, the device would deviate at most 2.6 Hz from the expected note. When given to participants, the number of correct strings played increased by an average of 2.8, 2.6, and 3.05 on the first three frets respectively when used as to when not used. The device was shown to increase average pitch accuracy by 82.53 Hz. 100% of users preferred using the device to not. The results show that users found more success in playing barre chords with the device and it assisted in decreasing the grip strength needed to play barre chords. In the future, the device can be made more portable and stronger motors can be used. In conclusion, this project created a device that increased accessibility for playing the guitar for people with decreased grip strength.

Research Proposal

Link to Research Proposal

Background

When a string is pressed down on a certain point on the guitar called a fret, the string is shortened, changing the pitch to create different notes or combined to play a chord. When playing a normal chord the musician will press their fingers on specific frets on different strings. Many guitarists use a type of chord called a barre chord where they press their index finger over all six strings on the same fret while the rest of the chord is played normally.Barre chords are difficult because a lot of grip strength is required. Beginners have trouble playing barre chords because they have not yet developed the grip strength necessary to play barre chords. The elderly have difficulty because body control decreases with age. This is represented in the decreased grip strength of the elderly population, especially in their hands. Those with medical conditions struggle with barre chords because of many common conditions such as Carpal tunnel and arthritis or more chronic conditions such as chronic kidney disease can negatively affect grip strength.

Procedure

Determining Materials
First, testing was done to determine the project's requirements. This included measuring the noise level of various materials when hitting the strings to find the material that produced the least amount of noise. Tests were also run to find the best motor to use for the project, determining each motor’s pressure against the string and its success in creating the correct pitch.

Creating a Proof of Concept
A rudimentary design was made to test the proof of concept. This design consisted only of the electrical components including an Arduino Uno, an L298N motor driver, a linear actuator, a button, a resistor, a breadboard, a 12V power adapter, and jumper wires. The design would retract/extend the actuator at the push of the button based on its current state. Initially, the actuator would not move when just connected to a power supply the motor driver and the Arduino. Because of this, the button system was implemented early which allowed the motor to be controlled.

Creating a Prototype
After finalizing the electrical components, 2D designs were created using SolidWorks to incorporate the electrical components. Measurements of the neck of the guitar were taken for the frame to fit against the neck. The frame went around the linear actuator and the neck of the guitar and would be pushed against the strings when the linear actuator extended. The top of the frame was made removable to allow the frame to get around the neck of the guitar. Subsequently, the 2D models were converted into 3D models. This model was printed, and the electrical components were incorporated. The prototype was adjusted as problems arose, such as a lack of motor pressure and the support system holding up the design. When creating the prototype, it was noticed that the movement of the grame and the linear actuator was quite slow and may have caused problems when attempting to play fast songs with the device. For this reason, the 9V battery power supply being used at the time was switched to a 12V power adapter which better matched the actuator's voltage. This exhibited greater speeds from the linear actuator. In addition, it was observed that the actuator would fully extend and then retract slightly when activated. To resolve this issue, the delay between the activation and deactivation of the motor in the Arduino IDE code was reduced to the point that there was no unintended retraction of the motor after extension.

Testing the Device
The control pitches for each string when barred were measured. The design was given to 20 human participants to test. The participants included young and old individuals, experienced and inexperienced guitar players, and those with and without physical disabilities that affected hand function. The participants were asked to play each string in an E major barre chord on the first, second, and third fret with and without the device while the pitch was measured. They were then asked to fill out a questionnaire about their experience with the device. The questionnaire first asked what demographics they fit into including age group, gender, experience with guitar, and medical conditions. It then asked users to rate their experience using a scale of 1-5. The participants ranked difficulty, comfortability, and ease of use. The survey ended with asking how their degree of hand strain changed with and without the device, whether they preferred playing barre chords with or without the device, and how they think the device could be modified to improve user experience.

Results

Analysis

When given to participants, the device was shown to increase average pitch accuracy when used compared to when not used. Across all frets, the device was shown to increase average pitch accuracy by 82.53 Hz. When observing whether the string was played correctly (if pitch deviance was less than 2.5 Hz), across all frets, without the device a a string was played correctly 26.05% of the time. With the device, a string was played correctly 69.19% of the time, showing a 43.14% increase in correctly played strings. When a paired t test was run on the pitch accuracy of the human participants with and without the device, a p value of less than 0.0001 was returned. The difficulty of playing barre chords with the device as compared to without the device from 1-5 was rated by participants on average as 4.65, with 1 being as difficult as without device and 5 being much easier than without device. The comfortability of the device to hold while playing from 1-5 was rated on average as 4.5, with 1 being the device was uncomfortable and 5 being the device was very comfortable. How easy the device was to control and use from 1-5 was rated on average as 4.2, with 1 being the device was very difficult to control and caused pauses in the music and 5 being the device was very easy to use and music was able to be played without interruption. 100% of participants said that the degree of strain on your hand and fingers decreased when using the device versus not using the device. 100% of participants said that they would prefer to play barre chords with the device.

Discussion/Conclusion

This project aimed to make playing the guitar more accessible to those with decreased grip strength by assisting the user in playing barre chords. The current method of barring the strings other than using your finger is to use a capo, a spring-loaded device that clamps down on the strings but cannot be moved while playing. When tested without a human participant, the device could produce barre notes with 2.6Hz pitch deviance or less. Since there is a 5Hz difference between adjacent notes on the guitar, this showed that on its own the device will consistently produce the notes in an acceptable range of the perfect pitch for the note to be considered correct. However, playing barre chords does not only consist of the barre; there are other notes in the chord. For this reason, it is expected that the device lessens the difficulty of the chord by playing the barre for the user. This is reflected in the data when the device was given to 20 Human participants. 90% of participants had no experience with guitar, falling into the target clientele of beginner guitarists. 25% of participants had Arthritis or Carpal Tunnel, falling into the target clientele of those conditions that affected hand function. 45% of participants were 65+, falling into the target clientele of elderly people. The results showed that the device makes playing barre chords easier for all, including the most venerable groups. Across all frets and strings there was an average of 43% increase in correctly played notes when using the metric of less than 2.5 pitch deviance. This meant users went from playing their notes correctly 26% of the time without the device to playing their notes correctly 69% of the time with the device. Across all frets, pitch deviance from the expected value was shown to decrease by an average of 83Hz for all participants, a 73% decrease. Examining these values, one can see that using the device increases the user’s success when playing barre chords. When a statistical analysis was run with a significance level of p less than or equal to 0.05, it was found that there was sufficient data supporting that there was convincing evidence that the usage of the device when playing barre chords increased the accuracy of the barre chord pitches. One limitation of the device is portability. To achieve sufficient power from the motor, the portable 9V battery had to be swapped for a 12V power adapter that needed to be plugged into a wall outlet. A second limitation is motor strength. If a more efficient motor was used pressure on the strings would have increased, creating a more accurate pitch.

In the future, this technology can be improved to achieve more accurate pitches. This would ensure the music played with the device sounds more correct and will assist in further making barre chords easier. In addition, it can be made portable. This will allow the device to be usable in various situations and will increase the number of places where it can be utilized, such as on stage without a power outlet. The device can be modified to increase compatibility with a variety of guitars. This will ensure the device is usable no matter the type of guitar the user owns. Finally, the device can be made easier to control and faster. This will ensure even the fastest piece of music will be able to be played with the device.

The objective of this project was to create a device that would make playing barre chords on the guitar more accessible. This was done by first finding out which materials would be the most successful in completing the project's goals. After this was done, a proof-of-concept design was created using only the electrical components of the device. A prototype was then made combining both the electrical components with 3D printed designs which worked together to press down all 6 strings. The prototype would produce notes with a maximum of 2.6Hz pitch deviance which is within acceptable range. The prototype was then given to 20 participants to test pitch accuracy. Without the device, the participants played a string correctly 26% of the time. With the device, the participants played a string correctly 69% of the time. The device was shown to increase average pitch accuracy by 82.53 Hz. This clearly shows that the device makes playing barre chords easier on the guitar, as success in playing barre chords increased when using the device as too compared to when not. In doing this, the device makes learning the guitar more accessible for everyone.