Author: ksabak

Last week’s focus was completing the design report. It has been uploaded to this site.

This week’s focus was creating the PCB design and ordering the PCB. The circuit diagram needed to be converted into a schematic for neatness. The circuit block diagram has changed during the PCB design process. The LED array now has start/end resistors, as indicated on page 10 of the SKC6812RV datasheet included in the Neopixel listing on Adafruit; capacitors are included, to decrease noise from power; and the mode control button now uses a pulldown resistor.

More parts have arrived; currently, the only missing parts are the plastic wrap, cord locks, and PCB. The PCB should arrive sometime this week, after which the electronic components can be attached and electronic prototyping can start.

One risk is schedule changes making it difficult to complete one working subsystem before the interim demo on April 1st. Certain tasks require previous tasks to be completed (for example, connecting Bluetooth to the web app requires establishing a secure Bluetooth connection on the Beetle), and we updated our Gantt chart to acknowledge that some future tasks (ex. Bluetooth-webapp connection) need to be pushed forward a week so that we can finish the tasks that they depend on (ex. Bluetooth connection setup in electronic prototyping). However, since we still have buffer time at the end of the chart, this is not as much of a concern as it could be. Our goal for the interim demo is that by working on the web app and bracelet in parallel, we’ll have at least one of those major subsystems done in time, even if they don’t talk to each other.

Survey feedback indicated that users would want a small, thin bracelet with a shorter (4-6 hour) battery life (as opposed to either a wide & thin or a small & thick bracelet with the original 8-hour battery life).

We have also decided to use exclusively plastic wrap for the exterior of the bracelet, since it comes the closest to meeting the sizing requirements when thicker plastic tubing is not used.

Finally, our schedule has been updated; the Gantt chart can be found here.

A screenshot of our Gantt chart

A) Global Factors [Lucy]:

Globally, hearing loss is one of the most prevalent disorders and is expected to rise by over 60% in the next few decades [1].  Our bracelet will serve as an easy and convenient way for people to check their sound levels. The bracelet is designed to be comfortable, durable, and practical to use for anyone that wants to be more aware of their surrounding noise levels. While our current use case is musicians, the bracelet is not limited to people in the music field. Anyone around the world that has a device that connects to bluetooth will be able to benefit from our product. The web application also is simple and easy to use. Even those who are not technologically savvy will be able to easily navigate through the user friendly interface to observe their sound level readings.

1. https://www.ncoa.org/adviser/hearing-aids/hearing-loss-statistics/#rates-by-age

B) Cultural Factors [Katherine]:

In many locations, cultural traditions and practices include musical education and performance. In order to ensure that these musical traditions continue, it is important to take steps to increase participant safety. Our project, which will provide easily-understandable visual feedback for awareness of participants’ sound environments, would allow participants to make more informed choices about their noise exposure levels (for example, practice time duration and frequency). This should allow them to continue safely interacting with music over longer timespans, allowing them to continue the musical traditions of their communities.

Considerations of beliefs and moral values do not apply to this product, because it only provides information to the user and does not suggest what actions they should take as a result. Language considerations apply to our project because the language used in the webapp needs to be both easy for the user to understand and scientifically accurate; in addition, text content should be in a language that users understand.

Laws are relevant to our product, including those regarding wireless transmission (since we are using a premade Bluetooth module, this consideration is taken care of by the creator). Also, even though our project should not and will not save audio data, the presence of microphones means that we should keep in mind laws about privacy. Someone could hack the bracelet and try to use it to illegally record conversations (Pennsylvania is a two-party consent state for recordings, as stated in https://www.dmlp.org/legal-guide/pennsylvania/pennsylvania-recording-law). For that reason, when developing this device, we need to make sure that the microphone data is only ever used to generate decibel values and cannot be used to record or save audio files.

C) Environmental Factors [Freda]

We predict that our device won’t have much effect on the environment. The materials used aren’t renewable or biodegradable, but then again what electronic components are? We decided on plastic casing because of its durable and clear qualities, which not many other materials we know of have (that are also readily available). Thus, we intend for our product to last a long time to help mitigate the pollution cost of materials, as well as advise users to dispose of e-waste properly (not with the regular trash).

In terms of specific living organisms affected, we don’t think the lights would be so bright as to blind others (and the lighting is also adjustable), so animals shouldn’t be harmed, and not sure how plants would be harmed either since they don’t really have eyes. (On the flip side, the lights are probably not bright enough to be used to keep your plants alive, either.) The most danger that animals could run into from this is if the user’s pet(s) decide to eat it, which is something that pet owners should already be aware of (since they have many other items that they don’t want eaten either), so keeping this bracelet safe requires no mitigation out of the usual measures.

What are the most significant risks that could jeopardize the success of the project? How are these risks being managed? What contingency plans are ready?

Unfortunately, our size requirements are most threatened by the battery size, because everything else can be quite small. Unfortunately, small and powerful batteries are presumably not on the market for proprietary reasons, so we can only have big bulky batteries. The battery we currently have will last for about 8 hours, which is the max time that one of our surveyed users wanted it to last for. Unfortunately, that means it must be bulky, either in the width or height direction. We are debating how necessary it is to cater to the person with the max time requirements, or whether we should focus on the lower time that the majority of the respondents stated, which is up to 4 hours straight. This would allow us to use lighter and smaller batteries, which would be more comfortable for the user. Thus, we will be asking our target demographic about these tradeoff decisions and what they would most prefer when we meet them on Monday.

As another option, we were also considering whether users could be able to swap out the size of the battery being used to fit their use requirements. Unfortunately that would add more designing of the battery pouch to make it fit both options (otherwise a smaller battery in a large bag wouldn’t save any space), and we’re not sure if this is something that’s really crucial.

Were any changes made to the existing design of the system (requirements, block diagram, system spec, etc)? Why was this change necessary, what costs does the change incur, and how will these costs be mitigated going forward?

The width requirement was returned in response to feedback in the design review Q&A, and modified to 70 mm to match the estimated width of the current design of our bracelet. This does not incur any specific cost at the moment; however, it might make the bracelet less comfortable for users. This potential cost will be identified if it exists through the planned integration test, and will be mitigated by rearranging the parts to create a bracelet with a width smaller than 70 mm.

Right now, the design only has one battery (because calculations showed that the bracelet might be able to meet the battery life specifications with only one battery) and two microphones (because there are only two Arduino digital input pins on the Beetle). A possible cost of using only one battery is that, if the components pull more current than expected, the battery life will not meet requirements. In that case, we would consult with staff to choose an alternate battery configuration that meets our requirements. A possible cost of using only two microphones is that there are fewer chances to correct errors; if one microphone’s input is incorrect, it has a greater effect on the overall calculation. We can mitigate this by processing microphone input in the code that converts microphone inputs to dB values.

Provide an updated schedule if changes have occurred.

The Gantt chart was updated; the most significant change is deleting a double-count of Bluetooth setup in both the hardware and software sections. We have extended some end dates for tasks, but the final parts of the project (integration and testing) have the same start/end dates, so the project remains on schedule overall.

This week, we worked on finalizing design choices in preparation for the design review next week. We also attended Professor Dueck’s class, where we could collect some preliminary data points for dB, check out some of the different rooms available, and ask for user feedback of what kind of product they’d prefer.

What are the most significant risks that could jeopardize the success of the project? How are these risks being managed? What contingency plans are ready?

One of the most significant risks we identified today is the possibility that the sizes of the materials we have chosen make it impossible to meet the sizing requirements we have set. We are managing this risk by relaxing our sizing requirements. We are also trying different prototyping methods that still try to minimize size as much as possible.

Were any changes made to the existing design of the system (requirements, block diagram, system spec, etc)? Why was this change necessary, what costs does the change incur, and how will these costs be mitigated going forward?

We have created a battery life requirement of 8 hours, which is the maximum amount of music-interaction time without a break that was brought up in conversation with participants in the music studio.  That creates the need for these relatively large batteries.

We are eliminating our thickness requirement. When considering preliminary sizing, we realized that the given dimensions of the parts we have agreed on (battery, microcontroller, LEDs, microphones, and boost converter) would not be feasible given the thickness and height requirements we had created. From there, we had a choice of eliminating the height requirement (creating a chunky bracelet) or the thickness requirement (creating a cuff/armband style of bracelet). We chose to eliminate the thickness requirement because eliminating the height requirement would make the bracelet stick out too much to be comfortable to wear (and would also make it more prone to damage). One concern with this solution is that it could interfere with wrist movements; given that our potential users include pianists, this is an important concern. We decided that the bracelet should be adjusted to be worn sufficiently far back that it does not cover the wrist or interfere with wrist movement. We will still attempt to minimize thickness, and rely on user feedback to determine if this is a satisfactory solution.

In our weekly meeting, we confirmed that connecting our components via a PCB is necessary. The alternative had been to individually solder/wire each component together, but this is probably impossible because of the size of the components. We are going to connect all non-battery components together on a flex PCB, and include a place to plug in the battery. This results in an increased cost for our system (from ordering the custom PCB).

Also in our weekly meeting, we discussed the idea of using 2 small batteries (instead of 1 large one); the battery life requirement dictates that we use larger batteries, but maintaining a relatively small size is important. Our plan is to use 2 small batteries, one on either “side” (above or below the wrist) of the bracelet, and have them wired in series to provide one red/black battery connection to the PCB. The risk is that, if done incorrectly, this can ruin both batteries; however, we are going to verify that our plan is safe before carrying it out, and take safety precautions while wiring the batteries together. In addition, if we test the bracelet and discover it uses less power than we thought, it’s probably easier to decrease the number of batteries than to increase it retroactively.

Provide an updated schedule if changes have occurred.

We have pushed forward tasks related to materials to account for the delay in finalizing and therefore in ordering materials. The tasks covering finalizing materials, ordering and receiving parts, electronic prototyping, Arduino-Bluetooth connection, LED signal setup, and the Bluetooth-webapp connection have all been moved forward to the week of February 25th. Also, software task deadlines have been moved forward because it took some time to get familiar with React Native; therefore, the deadlines have been moved to the 23rd and 25th, respectively.

This is also the place to put some photos of your progress or to brag about a component you got working.

Here are some sketches of our physical design.

How will our product meet a specified need…

with respect to public health, safety, or welfare? [Freda]

As mentioned in our introduction page, hearing loss was the leading sensory disorder in the US. Other than obvious uses such as listening to music and friends, our ears are also important to help with balancing, and even mild hearing loss doubles the risk of dementia [1]. In addition, people may not be as good at accurately interpreting the “loudness” of sound vs the actual decibel value, due to our ears being more sensitive to certain frequencies [2]. An objective way of measuring decibel levels, such as a phone app, would be nice, but inconvenient to pull out every time you want to check. Thus, a wearable device such as a bracelet would be a helpful way to monitor volume continuously throughout the day. This can be useful for musicians or other workers in loud environments, or anyone who wants to be more mindful of their surroundings. Once people are more aware of potential risks, they can take steps to mitigate and protect their hearing preemptively.

[1] The Hidden Risks of Hearing Loss | Johns Hopkins Medicine

[2] Equal-loudness contour – Wikipedia

with respect to social factors? [Lucy]

Our bracelet meets social needs by providing a convenient method for users to be more aware of their overall sound surroundings. With the adjustable light and color customization, our goal is to offer a product that caters to a diverse set of users, extending beyond those with full sight. Individuals with disabilities, like colorblindness, can also fully use our bracelet by customizing the colors to best suit their needs and preferences. Additionally, in settings where bright, flashing lights may be inappropriate, the bracelet can be customized to emit a softer glow. The light intensity can easily be adjusted to suit whatever the current social setting is.

with respect to economic factors? [Katherine]

The bracelet-webapp system is not meant to replace existing decibel meters and apps; therefore, it should have no effect on the production and distribution of these goods. While its goal is to create mindfulness of sound levels, the overall effect of this mindfulness remains to be seen. It is possible that increased mindfulness leads to users producing or consuming less music, because they are limiting their exposure. However, it is also possible that increased mindfulness will give users a better knowledge of when to take breaks, letting them engage with more music and therefore increasing their overall production and consumption.