Midway Design Review Team Vibraid November 2013

Vibraid Michael Balanov (Mike) EE Spyridon Baltsavias (Spiros) EE Reona Otsuka (Leo) EE Andrew Woo (Andy) EE

Assistive technology for the deaf community Fact: Over 5% of the world’s population – 360 million people – has disabling hearing loss Deaf/hard of hearing people have limited awareness of surroundings High demand but production of hearing aids meets only 10% of global need Currently deaf people have to use specific aids for different applications Expensive Impractical

Vibraid: Vibration + Hearing Aid Convert sound to vibration Research shows haptic feedback usefulness Lip-reading, frequency detection Alert user of impending danger/sound source Enable tactile sound localization

Physical Design Waist Belt Intuitive polar representation Horizontal orientation Relatively minimum obstruction Requirements Table SpecificationValue Circumference75-105cm (small-large) Width<10cm Thickness<2cm Weight<1kg

Previous Block Diagram

Revised Block Diagram Main changes: No Arduino – hardware implementation Filtering No light output switch signal variable resistance MDR Focus

MDR Deliverables PDR proposal: Sound to Vibration & Light Demo time! Additional Deliverables: progress towards 2-way directionality Input Block: Andy: Microphone requirement testing Spiros: Envelope Detector design Processing & Motor Block Mike: Comparator logic & motor activation Leo: Sensitivity logic & DC voltage testing

Input Block Purpose: Record sufficient sound data Pass it on for processing in a format suitable for amplitude comparison Microphone characteristics: 4 omnidirectional microphones (Freetronics.com) Vendor provided frequency response: 60Hz to 15kHz 2 outputs AC audio voltage “SPL” output DC voltage proportional to amplitude Mics placed in 4 locations (right/0°, front/90°, left/180°, back/270°) Requirements Table SpecificationValue Detection Directionality 4 directions Detection frequency range 100Hz to 10kHz, 90% of time Detection radius for 50dB-120dB sound within frequency range >3m (10ft), 90% of time

Microphone Range Test (Voltages) Procedure: Measure “SPL” voltage of noise Range: 0.00V-0.08V, depending on environment Measure “SPL” voltage of test-sound Computer-generated 440Hz tone Sound directed towards front of microphone Sound level from 3ft away: ~70dB (measured with dB meter application) Determine maximum range for which voltage>noise+0.1V Average Results: 10ft detection: yes 15ft detection: no

Microphone Frequency Response

Mic B Mic A Radius R Microphone Sound Detection Test (2 microphones) 15 in

Mic B Mic A Corresponding angle for each microphone 0/ /45 180/0 135/315 90/270 45/ /90 315/135 Degree relative to Mic A/ Degree relative to Mic B

Mic SPL Voltage Reading for various angles Mic #/Degree Mic #/Degree R = 10 inches R = 15 inches

Mic 2 Mic 1 Example Mic comparison 1.22/ / / / / / / /1.60 Voltage output of Mic 1/ Voltage output of Mic 2 Radius = 10 inches (#) = Stronger Mic at given location (2) (1) (1)/(2) (2)

Test Conclusion and Evaluation Inconsistency across each microphone Unexpected spikes/drops of voltage in some angles Microphones are not completely omni-directional No simple relationship between distance and sound amplitude Consider directional microphones

Input Block pt.2 “SPL” output

Envelope Detector Design

Input – DC Block – Amplification

Amplification – Rectification– Smoothing

Processing Block Purpose: Receive sensitivity knob input to determine if microphone input should be received Receive microphone output in order to compare amplitudes Determine quadrant of incoming sound Produce output signal with motor activation information to be read by Output Block Requirements Table SpecificationValue Vibration Directionality Simultaneous vibration in 2 adjacent locations Vibration response time <o.5sec

Processing Block Circuit Comparator/Sensitivity Logic DC testing Input 1 (V)Input 2 (V) Output (V)

Output Block Purpose: Receives control signals from Processing block Activates motors in appropriate location Indicates relative sound amplitude Motor characteristics “Coin” vibration motors, used in cellphones Noticeable vibration on skin Small voltage rating 2 motors per key location (front, back, sides) Requirements Table SpecificationValue Vibration Directionality Simultaneous vibration in 2 adjacent locations Vibration to corresponding detection 99% of times Vibration response time <o.5sec

Output Block Circuit Input 1 (V)Input 2 (V)NAND output (V)Inverter output (V)

Interface Block Purpose: Allow user customization for three features Microphone sensitivity Adjusts the threshold voltage for comparator block Frequency range detection Switches between 3 frequency filters and bypass Motor strength Modifies the motors strength according to user preference b Method Potientiometers for tunable voltage divider Switch to disconnect and reconnect to desired circuit Requirements Table SpecificationValue Tunable sensitivityBlock-all till pass-all Tunable frequency detection 4 modes: full range, 100Hz to 4kHz, 4kHz to 7kHz, 7kHz to 10kHz Tunable motor strength No vibration (0V) to Max supply (5V)

Output and Interface Potentiometers Motor strength Microphone sensitivity

Summary of Requirements SpecificationValue Belt circumference75-105cm (small-large) Belt width<10cm Belt thickness<2cm Product weight<1kg Detection directionality4 directions Detection frequency range100Hz to 10kHz, 90% of time Detection radius for 50dB-120dB sound within frequency range >3m (10ft), 90% of time Vibration response time<o.5sec Vibration directionalitySimultaneous vibration in 2 adjacent locations Vibration to corresponding detection99% of times Vibration response time<o.5sec Tunable sensitivityBlock-all till pass-all Tunable frequency detection4 modes: full range, 100Hz to 4kHz, 4kHz to 7kHz, 7kHz to 10kHz Tunable motor strengthNo vibration (0V) to Max supply (5V)

Gantt chart

CDR Deliverables Goal: Demonstrate 4-way detection and vibration directionality Correct quadrant determination Meet range, frequency specs Implement working user interface Prototype filter Implement levels of motor activation Portable power supply

Q&A

Power Specifications

Preliminary Cost Analysis

Pros and Cons of Design Pros Intuitive polar representation Horizontal orientation Adjustable Cons User may need to tuck in their shirt Hand/clothing obstruction