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

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.

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  Mobile Disadvantages:  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 ItemEstimatedActual Uni-Directional Microphones $30$16 Pre-AmplifierN/A$20 Signal AmplifierN/A$10 Vibrating Motor$20$18 68HC11 Micro-controller DEVL. Board 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