The Sound Sense Vibe
Outline Motivation for project Roles in project System Overview High level system design Business Case Project Details What Was Learned Future Work Conclusions Questions
Motivation for project
~ 6.5 million deaf people in North America.
Strong market for solutions.
Improving safety of the deaf via environmental awareness
Roles in project
JOHNSON
PATRICK
MIKE
JOHNSON
Pre-amplifier soldering and modification Revised design of signal conditioning amplifier PWM motor driver design Microphone “Shot Gun” enclosure Vibrating motors enclosure Hardware testing and wiring
Signal cable construction
PWM ISR instruction code Draft of A/D conversion ISR instruction code
PATRICK
Majority of Software A/D Capture & Summation ISR Main Program Loop Some PWM ISR Work
Amplification Stage Requirements & Testing Armband concept and creation High-level project design, requirements and testing
MIKE
Design and testing of the amp circuit Soldering of the Pulse Width Modulation
(PWM) driver circuit Post mortem Half of presentation
System Overview
The Sound Sense Vibe consists of four major components:
Microphone array Signal Conditioning Unit Microcontroller & Software Vibrating motor array
System overview
Microphones capture the audio
Signal Conditioning Circuit (pre-amp and amp) prepares signal for A/D converter
Microcontroller A/D converter digitizes signal
Software determines whether motor should be activated or not
Microcontroller Output port activates/deactivates motor
High level system design
Microphone A Preamp A Amplifier AMicro Controller A/D Channel A
PWM Motor A Vibrating Motor A
Microphone B Preamp B Amplifier BMicro Controller A/D Channel B
PWM Motor B Vibrating Motor B
Microphone C Preamp C Amplifier CMicro Controller A/D Channel C
PWM Motor C Vibrating Motor C
Microphone D Preamp D Amplifier DMicro Controller A/D Channel D
PWM Motor D Vibrating Motor D
Signal Aquisition Signal Conditioning Signal Processing Actuator Interface
Signal Acquisition
Four unidirectional microphones Noise filtering Pre-Amplification Output signal 0.7 V
Signal Conditioning
Amplification Output is from -2.5V to 2.5V
Level shifting Output is from 0 V to 5 V
Variable resistor Variable DC offset Enhanced stability Ensures proper output shifting
Signal Processing
10 KHz sampling rate Approximate signal
integration to find signal power for a fixed window
Use this power and a threshold to determine if a motor should be on/off during window period
Actuator Interface
Four vibrating motors Pulse Width Modulation
(PWM) driver. PWM signals drive transistor
into saturation Power to motor controlled by
pulse bandwidth Current limiting resistor Diode preventing startup
spikes.
PWM Input
M
Electric Motor
Collector Current Limit Resistor
+Vcc
GND
Surge Protection Diode
Business case
Competition
Cost
Market
Competition
Cochlear implants
Hearing Aids
Alert Devices
Multi-Purpose Alert Devices
Cochlear implants
Direct connection between nerve endings in the brain and the hearing aid.
Advantages: Users can regain the ability to
understand speech Device completely bypasses possibly
damaged inner ear and cochlea works Even in cases of profound
deafness MobileDisadvantages: Very expensive ($60,000+). Requires rehab to refamiliarize user
with sounds Cannot fully reproduce sounds Only some deaf people are suitable
candidates.
Hearing Aids
Amplifies sound for the ear most common device for the hearing
impaired.
Advantages: compensates for the gradual decay of
hearing widely available Mobile
Disadvantages: Cannot help those with profound
deafness Still moderately expensive ($300+)
Alert Devices
Alarm triggers receiver which notifies user via vibration or lights.
Advantages: Fairly Cheap Ensures the user is alerted to
specific events
Disadvantages: Non-mobile (limited to the
domicile) Requires replacement of existing
doorbells/fire alarms/alarm clocks
Multi-Purpose Alert Devices
Programmable to recognize certain noises and alerts user.
Advantages: Priced between hearing aids and general alert devices Can be trained to recognize events for alerting Mobile
Disadvantages: Rare (not available anywhere on market in large volumes) Can be difficult to setup
Cost
The total cost of all components in our project was ~$300 (see budget for more info)
Final miniaturized version should still be sub $500
Comparable to a hearing aid
Market
Our product fits into a unique area not covered by any competing products
TARGET: profoundly deaf not suitable for hearing aids cannot afford cochlear implants not suitable patients for the
surgery. Workers in high noise
environments (Airport tarmac workers, etc.)
Project Details
Project Budget: Stayed fairly close to
original budget Amplifier stages were
not foreseen
Item Estimated Actual
Uni-Directional Microphones
$30 $16
Pre-Amplifier N/A $20
Signal Amplifier N/A $10
Vibrating Motor $20 $18
68HC11 Micro-controller DEVL. Board
Free Free
Arm Attachment $20 $16
Misc. Expenses (Shipping etc)
N/A $10
Total: $70 $90
Schedule
What Was Learned
Plan Carefully Test early and
frequently Integration never
works the first time Even simple signal
processing can be difficult
Future Work
Add calibration UI Better positional
performance Miniaturization Better armband for
comfort and feedback prevention
Conclusions
Accomplished a lot in a small amount of time Heavy limitations in terms of time and resources Good proof of concept device performs what we
hoped it would Project provided a good combination of
disciplines: electronics, real-time embedded programming, signal processing, usability
Questions