Group 9 (VARPEX) – P6

Group Number and Name: Group 9, Varpex

Group Members: Abbi, Dillon, Prerna and Sam

Project Summary: Our project provides a new musical listening experience through a jacket that vibrates with the bass.


Over the past few months, we have developed a jacket that provides a new means of experiencing music. There are 12 motors that line the jacket and provide sensation. There is a box that plugs into the jacket and produces the sensation. A user puts on the jacket, plugs in their headphones and MP3 player to the box, and connects the jacket to the box. They play their music using their MP3 player and this causes vibration of the motors. In this report, we evaluate the ease of setup of the system and how well it provides an enjoyable experience for our users. This experience includes both listening to music with the sensation of the motors while sitting and walking and the experience when the music is off and participants wear it as they would a normal jacket.

Implementation and Improvements

Please click here for our P5 submission

Changes since P5:

  • New box: We switched to a plastic box because we were concerned about the possibility of the cardboard igniting from a spark should something go wrong with the electronics.

  • We labelled the ports on the box for clarity.


1. Participants

We solicited volunteers through our eating clubs and student organizations. The students that responded expressed interest in trying our prototype, knowing that its purpose was providing a new way of experiencing music. The students that ultimately tried the jacket all enjoyed music, but often of different genres. All enjoyed the feeling of music experienced when listening to live music. We tried to draw from the general student body so these students had a wide range of technical and musical knowledge. Participants were all aged 19-21, students at the university, and live in dormitories.

2. Apparatus

The tests were conducted in the undergraduate ELE lab. We chose to perform the tests there so we could more easily troubleshoot any technical problems with our system. The equipment we used were a set of headphones, a phone-based mp3 player, our jacket of embedded motors and the box containing our system. These items together represent the complete set-up one would need to actually use our system in a non-lab setting, so we are confident that the testing we do today represents well how someone might actually use our system to feel music in real life.

3. Tasks

As in the past, our system does not exactly conform to the “three tasks” paradigm. Our study, however, does try to give the user a sense of how they might use the jacket in one of the three settings we have described previously: listening to music in your room (easy),  listening to music in a public library (medium), listening to music while walking out and about (hard). They are little changed from P5. These tasks represent three times when people commonly listen to music via headphones. In this scenario, participants listened to music first while sitting in a chair as well as while interacting with us for the first part of the testing phase. We then had the users stand up and walk around the lab a few times while listening to music. These scenarios gave us a good idea of how users would react in the three original tasks.

4. Procedure

We first welcomed our participants and they filled out the consent form and the first page of our google form. This form asked demographic information and asked about music preferences. After they filled out this initial form, we explained the system to the user and asked them to set it up. We gave them an overall description but did not give them specific instructions for setup. Participants then set up the system and asked questions when necessary. We asked for their initial feedback on the setup process and confusing aspects of the design. Next, we had them listen to music for few minutes however they felt comfortable. We then asked for their feedback about the jacket without any music playing (and no vibrations). We also went through a series of questions to understand how pleasurable the experience was and where it could be improved. As we interviewed participants, we observed their behavior for fidgeting and signs of discomfort. Participants then walked around with the system to test how it felt while walking. We asked for feedback on comfort and sensation in this task as well. At the end, we opened a general conversation with the participant about the experience and asked how it could be improved.

Test Measures

As mentioned before, our prototype is not directed towards helping a user improve any sort of objective measure of a task. Therefore our testing sought to solicit subjective evaluations of things like comfort, sensation, and likelihood of using the jacket for one of the three tasks we thought would be good usage scenarios.

We ultimately collected a wide variety of subjective measures. Questions regarding ratings were asked on a scale of 0-5. For the full list of questions, see the Google form in the appendix. The subject matter of the data collected included:

Demographic Data:

  • Musical preferences/opinions of electronica
  • Frequency of concert-going
  • Frequency of music-listening outside of live music setting

Ease-of-use data:

  • Logs of users attempting to use jacket with little-to-no instruction
  • Self-evaluation of difficulty in putting on jacket
  • User perception of valuable information in jacket-use instructions

Comfort/Likelihood of use data:

  • Comfort of jacket relative to a non-vibrating jacket when jacket is off.
  • Comfort of jacket while sitting down and standing up.
  • Adjectives used to describe jacket.
  • Likelihood of using jacket relative to amount user currently listens to music in different settings.
  • Desire to own jacket.

Results and Discussion

Our test subjects came to us with a diverse array of musical interests- when asked for their top three musical genres, over 12 distinct genres were named among the subjects. Interestingly only one of them named “electronica” in their top three, which was one of the genres we had targeted as a good candidate for “feeling” music. No matter what their tastes were reported to be we first had the users test the jacket using the song “Thunder Bay” by Hudson Mohawke. One of our users who described dubstep as “overrated, boring, tuneless” still reported a positive experience with the jacket, describing it as “fun” and “interesting.” When we asked users to try the jacket with their preferred music, however, they responded much more positively- that same user with a lower opinion of dubstep and electronica later tried the jacket with music from her favorite artist (“Bad Romance” by Lady Gaga), and reported an even more positive experience. This is a promising development that could expand our target user base, but it will require some modification of the jacket. Currently, the jacket is capable of responding to frequencies below 160 Hz. The intensity of vibrations is controlled by a comparator which allows current to flow through the motors for a particular fraction of the given low frequency wave. In genres like dubstep with lots of heavy bass, this fraction can be fairly low and still produce lots of sensation since the dominating frequencies are below 160 Hz. In other genres, the concentration of bass is lower so this fraction needs to be increased to produce a comparable sensation. We can give the user the ability to adjust this fraction using a potentiometer so they can calibrate it themselves to the best sensitivity of their preferred music. (Perhaps this could even be done in a future iteration on a microcontroller like the Arduino, where a simple pre-processing step could analyze a song to find the ideal threshold level with no overhead for the actual performance of the jacket). It’s certainly a functionality that people seemed to expect already; it appeared that people would play with the volume knob in our usability test in the expectation that it would modify the sensitivity of the bass already, so adding that function is definitely appropriate.

We were also pleased to see that users rated the comfort of the jacket highly- on a scale of 0-5, 0 being not at all comfortable and 5 being as comfortable as any other jacket, the users rated the jacket on average as a 4.1 when worn while sitting down, and a 3.5 when standing up and walking. There were other factors, however, that affected the user experience when wearing the jacket. Users- generally women of shorter stature- reported that the jacket’s loose-fit may have interfered with their ability to receive the full effect of the vibrating motors. Further, no one said that they would describe the jacket as “fashionable.” Three of the users even went as far as to say they would describe the jacket as “ugly.” Jacket fit between users was always going to be an issue, since a men’s hoodie can only fit so many people. In a next iteration however we will try to make the vibrating motor assembly more easily secured to the jacket using velcro rather than sewn-on pockets for the motors. That way, it can be more easily placed in jackets of varying style and size. Another inhibiting factor on user comfort was the fact that while up and walking, the users had to carry around the box containing our system with them. This was unfortunately a limitation on our prototype, which was implemented on two small breadboards attached to the three 9-volt batteries needed. In our next iteration we are exploring the possibility of soldering the project to a protoboard to allow for a more portable form-factor. In the meantime, we have to put the issue of the large box aside as our own version of a “wizard-of-oz” set up, since we never really expected that users would have to carry it around.

People generally found the jacket easy and intuitive to use, but certain prototyping aspects were noted to be cumbersome. The test subjects all said that having to carry around a bulky box was inconvenient, and a more intuitive plug and play interface easily built into the jacket would be preferable. Test subjects also found the direction of the volume knob unintuitive since it rotated in the opposite direction to standard knobs. Both these interface issues are ones which we plan to address and fix in the next prototype. Another important design idea which emerged from this stage of testing was customizability. Fit of the jacket was a problem for some test subjects, and we believe it can be addressed by redesigning the jacket into a frame of motors that can potentially fit into many different jacket sizes. While this design isn’t something we can implement in the next iteration, it is a good idea for future design changes. In summary, we would like to implement the following changes to our jacket for the next iteration:

  • Change the direction of the volume knob to make it more intuitive.
  • Integrate the circuitry into the jacket so the wearer is not required to carry the box.
  • Add a threshold knob so the sensations can be customized based on individual comfort levels.
  • Make the power switches more accessible to ease the plug-and-play interface design.

The three main tasks we listed when thinking of use cases for our jacket were as follows:

  1. Listening to music while walking to class
  2. Listening to music while studying in the dorm room, library or other such quiet place.
  3. Listening to music while in a silent disco.

Our test subjects said they would use the jacket under all the three listed situations. The idea of using it at the Silent Disco was very popular, but while thinking about performing everyday tasks, testers were concerned about the storage of the jackets when not in use. One of the testers was concerned about walking around with the jacket, and how the process would work with motors and wires in the jacket. Final additional concerns that were raised included wearing a jacket in warm weather, its durability, and its washability. These are secondary to our primary goal of creating a new music listening experience but will be key in future iterations of the jacket.


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