1. Tactile Auditory Sensory Substitution
Jimmy Fong, Jack Page, Becky Jones, Ryan Thome, Matt Valaskey
BME 400
October 19, 2007

2. Dept. of Biomedical Engineering & Dept. of Ortho-Rehab Medicine
Client:
Veronica H. Heide, Au.D.
Audible Difference
Advisor:
Mitchell E. Tyler, P.E., M.S.
Dept. of Biomedical Engineering &
Dept. of Ortho-Rehab Medicine
University of Wisconsin - Madison

3. High Frequency Hearing Loss
Sensorineural
Normal hearing = 50 – 20,000 Hz
Above 1,000 Hz is lost
Loss of ability to hear certain high frequency consonants
Like hitting piano key with no strings
Krames Communications.

4. Problem Statement
The goal is to design and develop an auditory substitution device that through the use of vibro-tactile stimulation can substitute for regional frequency hearing loss. The main focus of this semester is to complete the housing design, develop a real time prototype, and to start human testing.

5. Sensory Substitution
Presenting environmental information absent in one sensory modality to another
Examples:
Long Cane - visual navigation substituted though touch
Sign Language - speech substitution through vision
Braille - visual text substitution though touch

6. Sound Processing “Sixty – Fifty”
Channel to Frequency
Breakdown
1: kHz – p, i, m
2: kHz – ch, sh, f
3: kHz – ch, sh
4: kHz – s, th
“Sixty – Fifty”
Pairs of words that can be distinguished with device
Sixty versus Fifty
Shirt versus Church
Much versus Such
Sob versus Shop

7. Prototype Runs on two 9 V batteries Current draw: ~ 150 mA
Costs:
Circuit Components: $10.16
Roadie Sound Card: $49.99
Motors: $15.96
Attachment: $2.00
Total: 78.11
Runs on two 9 V batteries
Current draw: ~ 150 mA
Expected battery life: ~ 12 hr

8. Modifications and their added benefit
Prototype will be real time
Handheld device:
Easier discrimination between
vibrating transducers
Less attachment difficulties
Further research indicates
benefit to adjusted frequency bands
Channel breakdown:
1: 1.6 kHz – 2 kHz p
2: 2 kHz – 3.5 kHz sh, ch, k
3: 4 kHz – 6 kHz s, t
4: 6 kHz – 8 kHz th, s

9. Placement & Housing Specifications Handheld 9X4X4 cm
One tactor in contact with each finger
Tactors embedded in viscoelastic memory foam
Small raised surface on motors
Durable, plastic covering

10. Real Time Digital Processing
Input sound data via microphone (A/D converter)
Write FIR filters in C and load onto DSP
Digital output to four pins of parallel port
Attach motors via parallel port cable
TI TMS320C6713 DSK

11. System Diagram with Modifications

12. Future Work IRB Approval Construction of new prototype
Human subjects testing of our device
Analysis of data from human subjects testing
Make any necessary modifications to design bases on data analysis

13. References
Krames Communications. (1995). Hearing Aids. [Brochure]. San Bruno, CA.
Audiological Engineering Corp. (n.d.) Tactaid 7. Retrieved 29 September, 2006 from
Kanyo, M. et al A Tactile Synthesis Method Using Multiple Frequency Vibrations for Representing Virtual Touch. IEEE/RSJ. p 1121 – 1127.