Tactile Hearing Aid Demonstration ENSC 440 – Group 14 David Dickin Mehran Eghtesad Ryan Dickie Merle Kinkade Simon Fraser University April 2007

Copyright 2007 Pivit Technologies Inc.2 Outline  Introduction  Software Subsystems  Hardware Subsystems  Business Case  Experimental Results  Conclusion  Demonstration

Introduction

April 2007Copyright 2007 Pivit Technologies Inc.4 Team Members  David Dickin – CEO  Mehran Eghtesad – Senior Hardware Designer  Ryan Dickie – Senior Software Designer  Merle Kinkade – CFO

April 2007Copyright 2007 Pivit Technologies Inc.5 What is a Tactile Hearing Aid?  A device that translates noise into touch  Used to help the hearing impaired  Traditional hearing aids cannot be used by all people

April 2007Copyright 2007 Pivit Technologies Inc.6 System Overview

April 2007Copyright 2007 Pivit Technologies Inc.7 Subsystems

Software Subsystems

April 2007Copyright 2007 Pivit Technologies Inc.9 Technologies  Wav Reader/Writer: self-designed.  FFT: FFTW (Fastest Fourier Transform in the West)  Audio Input/Outer: Windows Multimedia Library  Parallel Port: Inpout32.dll  Drawing: GDI  GUI : Winapi  Misc: Boost C++ libraries

April 2007Copyright 2007 Pivit Technologies Inc.10 GUI User Interface

April 2007Copyright 2007 Pivit Technologies Inc.11 Audio IO  Runs in separate threads  Hz, 16-bit, mono  Can load/save to wav files  Can use microphone input

April 2007Copyright 2007 Pivit Technologies Inc.12 DSP  Hamming Windows  R2C DFT with N = 4096  Threshold Filtering  Critical Transform  Bins  Buzzer Amplitude Mapping

April 2007Copyright 2007 Pivit Technologies Inc.13 Parallel Port Interface  Runs in a separate thread  Updates in 1ms intervals  Buzzer amplitude achieved by pulsing buzzers  Uses inpout32.dll driver

Hardware Subsystems

April 2007Copyright 2007 Pivit Technologies Inc.15 I/O Control Board  PCB fabricated to drive vibrators  Connects software to VibraPad  UI is on/off switch and intensity knob

April 2007Copyright 2007 Pivit Technologies Inc.16 VibraPad  Why 16 Vibrators? Parallel port limitations Space limitations Power restrictions  Worn on stomach/torso area Largest even surface area without contour issues Large network of nerve endings  Velcro for repositioning and ease of array placement

April 2007Copyright 2007 Pivit Technologies Inc.17 Proposed Mappings Uniform Offset Offset with Snaking Offset with Snaking & Natural Mapping

April 2007Copyright 2007 Pivit Technologies Inc.18 Transforms/Mapping  Critical Bands based on Frequency Response of Human Ear  Critical Band Mapping based on Bark Scale  Below 500Hz  Uniform bands of 100Hz intervals  Above 500Hz  Bands increase non- uniformly with Frequency

April 2007Copyright 2007 Pivit Technologies Inc.19 Bark Scale Divisions High resolution below 500Hz Human voice ~500Hz–2kHz Optimum range ~2kHz– 4kHz Resolution decreases Rapidly above 4kHz

Business Case

April 2007Copyright 2007 Pivit Technologies Inc.21 Budget and Funding

April 2007Copyright 2007 Pivit Technologies Inc.22 Schedule

April 2007Copyright 2007 Pivit Technologies Inc.23 Market Overview Statistics obtained from publications of the National Institute on Deafness and other Communication Disorders (NIDCD) based on the American population and published at

Experimental Results

April 2007Copyright 2007 Pivit Technologies Inc.25 Goals “The purpose of this project is to determine the extent and limitations of the tactile sensory system to receive and translate sound information. Such measures will be quantified by outlining specific test procedures and conducting these tests on several individuals.” Project Proposal Criteria for Success “To deem a series of experiments successful, a minimum hit rate of 80% must be achieved after a maximum of 100 minutes of cumulative training, or 5 iterations of the above experiment.” Design Specifications

April 2007Copyright 2007 Pivit Technologies Inc.26 Experiment 1 Procedure  10 short sound clips Sirens, bells, animals, vehicles, etc.  Subjects allowed to hear sounds  Training time One by one with audio: open ended One by one without audio: open ended Random: max 10 minutes Operator-assisted training: max 10 minutes  Two set of Transforms

April 2007Copyright 2007 Pivit Technologies Inc.27 Transforms  Transform 1: Frequency bins determined based on critical bands  Transform 2: Frequency bins divided equally in log scale BuzzerFrequency Range (Hz) Transform 1Transform

April 2007Copyright 2007 Pivit Technologies Inc.28 Experiment 1 Results Conducted on 4 people  Transform 1: Average Hit rate: 95% Average Training time: 20 min PASS  Transform 2: Average Hit rate: 100% Average Training time: 16 min PASS TOO EASY?

April 2007Copyright 2007 Pivit Technologies Inc.29 Experiment 2 Procedure Changes from Experiment 1  30 short sound clips  Normalize length of clips (3-4 sec)  Subject not allowed to hear sounds

April 2007Copyright 2007 Pivit Technologies Inc.30 Experiment 2 Results Conducted on 4 people  Transform 1: Average Hit rate: 55% Average Training time: 43 min FAIL  Transform 2: Average Hit rate: 53% Average Training time: 35 min FAIL TOO HARD?

April 2007Copyright 2007 Pivit Technologies Inc.31 Redesign Changes  Based on user feedback and comments as well as our personal observations  Create Transform 3: compromise of uniform and critical band  Change VibraPad layout  Change different intensity levels (PWM)

April 2007Copyright 2007 Pivit Technologies Inc.32 Vibrator Layout Experiment 1/2 LayoutExperiment 3 Layout

April 2007Copyright 2007 Pivit Technologies Inc.33 Experiment 3 Procedure  Large scale test (20+ subjects)  10 short sound clips of the same length Sirens, bells, alarms, cars, etc.  Limited training time Self directed: 7 minutes Operator-assisted: 7 minutes  Provide a list of sound names to subjects  Using transform 3

April 2007Copyright 2007 Pivit Technologies Inc.34 Experiment 3 Results Conducted on 23 individuals  Average hit rate: 68%  Average training time: 17.5 min

April 2007Copyright 2007 Pivit Technologies Inc.35 Experiment 3 Results  Previous exposure Our group: 97.5% Everyone else: 61%  Age 16 Individuals under 35: 77% 7 individuals over 35: 44%

Conclusion

April 2007Copyright 2007 Pivit Technologies Inc.37 Summary  Participants are able to identify sounds with practice  High pitched sounds, like alarms, are easy to distinguish  More testing required, but has some marketability  Project stayed on schedule and budget

April 2007Copyright 2007 Pivit Technologies Inc.38 Acknowledgements  Thanks to the ESSEF and the Wighton Fund for funding for our project  Thanks to the ENSC 440/305 Professors and TA’s for their time and assistance

April 2007Copyright 2007 Pivit Technologies Inc.39 Questions? Go Canucks!

April 2007Copyright 2007 Pivit Technologies Inc.40 Similar Devices  Audiotact  Tacticon  Tactaid

April 2007Copyright 2007 Pivit Technologies Inc.41 Bark Scale Divisions

April 2007Copyright 2007 Pivit Technologies Inc.42 Standards  Standards Council of Canada  CSA  ANSI  ISO  FCC  ECMA