Download Tactile Auditory Sensory Substitution - Computer

Tactile Auditory Sensory
Substitution
Ryan Thome, Sarah Offutt, Laura
Bagley, Amy Weaver, Jack Page
BME 200/300
October 20, 2006
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
Overview
Problem Statement
 Background
 Proposed Designs
 Future Work
 Questions

Problem Statement
The goal is to design and develop an
auditory substitution device that through
the use of a digital hearing aid and either
vibro- or electro-tactile stimulation can
substitute for regional frequency hearing
loss.
PDS Summary
Adjusts to user specific hearing loss
 Works with digital hearing aid output
 Use vibro- or electro- tactile stimulation
 Not highly noticeable (discrete or
aesthetically acceptable)

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
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.
Existing Devices

Tickle Talker



Tactaid 7


Electric shock on sides
of fingers
One electrode per range
of frequency
Vibro-tactile stimulation
on sternum, abdomen,
forearm or neck
Tacticon 1600
http://us.st11.yimg.com/us.st.yimg.com/I/audiologic
alengineering_1903_431188
Digital Hearing Aid
Two main types:
In-the-ear (ITE)
Behind-the-ear (BTE)
 Frequency range 100 Hz – 7300 Hz
 Takes analog waveform and converts it to
string of numbers
 Gain processing, digital feedback
reduction, noise reduction, speech
enhancement

Sound Processing Unit
Obtains high frequency signal from
hearing aid
 Amplifies signal
 Several channels of frequency
 Channel signals corresponding tactile
stimulus to fire

Electro- vs. Vibro-Tactile Stimulation


ElectroPros




Less power
consumption – 1.2mW
per 3 mm electrode
Smaller
Easier construction
Cons



Potential for shock and
burns (only @ v. large
current)
Sensation quality varies
Limited dynamic range
of sensation


VibroPros



Less variation in
sensation
Comfort
Cons



More power
consumption - 138 mW
per 4 mm electrode
Harder to attach
More complex
construction
Placement

In the ear

Pros


Cons



Less space for differentiation
More complex construction
Behind the ear

Pros



Mostly concealed from outsiders
Easy access to hearing aid
Cons


Completely concealed from outsiders
Attachment impeded by hair
Neck

Pros



Most space for tactile layout
Easiest construction
Cons

Easily noticeable to outsiders
Alternative Design 1 & 2
Design 1
Design 2
Electro-Neck
Vibro-BTE
Proposed Design
Electro-BTE
• Array of electrodes aligned
vertically behind ear
• Each electrode corresponds to
certain frequency range
• As frequency increases each
corresponding channel signals
the electrode
Future Work
Decide on components
 Design and build signal processing unit
 Determine two point discrimination
threshold
 Analyze signal from hearing aid and break
into channels

Design Matrix
Power
Consumption
ElectroNeck
5
Vibro-Ear
Electro-Ear
1
5
Safety
4
5
4
Ease of
Manufacturing
4
2
4
Patient
Comfort
3
4
4
Aesthetics
2
4
4
18
16
21
Total
References
Krames Communications. (1995). Hearing
Aids. [Brochure]. San Bruno, CA.
 Audiological Engineering Corp. (n.d.)
Tactaid 7. Retrieved 29 September, 2006
from
http://www.tactaid.com/tactaid71.html.

QUESTIONS