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Introducing tRacket

A low-cost way to track noise

Civic Tech Toronto hacknight, July 23 2024

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The problem & inspiration

Noise isn’t just an annoyance: research shows that health impacts of noise can include cardiovascular effects, sleep disturbance, mental health, and pulmonary disease.�
Negative health impacts can start at levels as low as 42 – 60 dBA (Leq).

No More Noise Toronto has been very effectively advocating�for greater awareness about urban noise in Toronto.

Noise isn’t just annoying; it turns out that it’s actually bad for your health. (And it’s not just about hearing loss.)

Ingrid at No More Noise Toronto has been pointing this out to Torontonians. Just because we live in a city doesn’t mean that we can’t experience quiet, or a decent night’s sleep.

As Ingrid says, pretty much everyone in Toronto has a noise story, and that includes us. We were inspired by Ingrid’s work, and wanted to see if there’s something we could do to help.

We noticed that while the negative impacts of noise over 60 decibels is well-established, it’s surprisingly difficult to get data about what actual noise levels are, around us. If you decide to start learning about it, you end up looking at these devices that companies sell for hundreds or thousands of dollars, are really awkward to use, and are normally only really designed to be installed for days or weeks.

What we wanted was to have data that would help us understand the patterns of noise in our neighbourhoods, and how it changes over time. To do that, we needed a way to collect data over years. We couldn’t find any devices that could do this, at least in a way that was easy and cheap. So we decided to try to make one!

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Fixing the scope

Always-on sensor, wifi-connected
Data stored online
Low-cost, easy to use
Open data
Privacy by design / data minimization

The only data we collect is:

Noise level (decibels)
Date/time
Device ID
Location
Email address

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Ideation and prototyping

It started as a mobile app!�
Then a messy breadboard prototype�
Then a custom printed and assembled circuit board�
Then some nice 3-D printed enclosures�(Thanks, Albert!)

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tRacket system

Sensor

API

Database

Sensor Manager

Dashboard

Website

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The sensor

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Early Prototype

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First Printed Circuit Boards (PCBs)

Designed using KiCAD
Manufactured by JLCPCB
Custom 3D-printed enclosure
Cost: $34 per board + $2 3D-print

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"Rev 2" PCBs

Manufactured by Ocean Smile PCB
Off-the-shelf enclosure with�hand-drilled ports
Cost: $23 per board + $4 enclosure

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Sensor Firmware

Written in C++ using the PlatformIO/Arduino framework
Hosted on GitHub

3 contributors
>160 commits

Device setup via access point
Encryption for user information
Automatic and secure wireless updates

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API, Database and �Sensor Manager

F1894D

Sensor

API

Database

Sensor Manager

Dashboard

Website

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API

Sensor

API

Database

Sensor Manager

Dashboard

Website

(Mitch, 1 of 3 minutes)

The API is at the center of things. All components communicate with the API to send and receive sensor data.

It receives information from Sensors:
Sensor registration: Sensor ID, Owner Email
Sensor measurements: Sensor ID, Time, dB Levels (5 minute min, max, mean)
It receives configuration options from the Sensor Manager:
Sensor location: latitude, longitude, privacy radius
Sensor notifications: enable/disable
It stores all of this information to the database.
It sends Sensor Location and Measurements to the Dashboard when requested, as well as third-parties (open data).

It also sends a generated Secret Token back to the sensor upon registration.
It sends Email Notifications to sensor owners upon registration and inactivity (sensor hasn’t sent a measurement in 30 min, 1 day, 1 week).

Technically speaking, the API is a REST web service written in PHP (leverages the webCOMAND PHP API).

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Database

Sensor

API

Database

Sensor Manager

Dashboard

Website

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Sensor Manager

Sensor

API

Database

Sensor Manager

Dashboard

Website

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Sensor Manager

Sensor

API

Database

Sensor Manager

Dashboard

Website

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Tech Stack

Backend

Frontend

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The dashboard

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Dashboard

Sensor

API

Database

Sensor Manager

Website

Dashboard

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Dashboard User Flow

Location Dashboard

Navigate to a device and explore noise measurement

System Map

Discover the map and start exploring locations

Website

User arrives at the website for the first time

First-time User

Returning User

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The Map

Inactive Location

Active Location

Location Cluster

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Metrics

Last Week’s Hourly Noise

Current Hourly Avg & Trend

Location Bubble

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5-min resolution

Hover and Zoom for more info

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Tech Stack

Dashboard Backend / Frontend

CI / CD

Hosting

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The website: tRacket.info

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Current status

tRacket is fully-functional, and in a testing phase!�
Sensors are currently available only to volunteers/contributors – we’ll send out notice on our mailing list when we’ve got more.�
Sensors will eventually cost around $50 each, �not including the power supply or USB cable.

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What’s next

We have an updated dashboard in development�
Branded sensors�
User research�
Ordering and fulfillment?�
Community workshops

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