Vibraid Michael Balanov, Spyridon Baltsavias, Reona Otsuka, Andrew Woo Faculty Advisor: Prof. Ramakrishna Janaswamy Department of Electrical and Computer Engineering ECE 415/ECE 416 – SENIOR DESIGN PROJECT 2014 College of Engineering - University of Massachusetts Amherst SDP14 Abstract Block Diagram System Overview Specifications Acknowledgements Hearing-impaired people often face difficulties in everyday life, including potentially limited situational awareness due to delayed or missing reaction to important sound stimuli. The Vibraid, a tactile wearable aid device, provides a solution to this issue by implementing a simple concept: sound to vibration conversion. Through haptic feedback in different locations around the waist, it allows a user to detect incoming sounds, such as fire alarms, car horns and emergency sirens, as well as their direction in the azimuthal plane. As a result, the Vibraid’s simple, intuitive, and cost-effective design compiles features of many existing hearing aids while providing extensive customizability to the user for safe navigation in indoor and outdoor environments. We would like to thank our advisor Prof. Janaswamy for his constant guidance and support throughout the year as well as our evaluators, Prof. Ciesielski and Prof. Kwon for the constructive feedback. Finally, our project would not have been successful without the help of Prof. Hollot, Francis Caron, and the Disabilities Services staff. SpecificationValue Max Detection radius for 70dB to 120dB within frequency range >3m (10ft) Frequency Detection Range100Hz – 10kHz Belt Circumference75cm – 105cm (small – large) Belt Width<10cm Belt Thickness<5cm Product Weight<1kg Detection Directionality4 Directions Vibration Response Time<0.5s Vibration DirectionalityVibration to alert user in one quadrant Vibration to Corresponding Detection99% of time Tunable SensitivityBlock all till Pass all Tunable Frequency Detection4 modes: full, low, mid, high Tunable Motor StrengthNo vibration to Max supply Battery Life>12h The Vibraid comprises a belt with four uni- directional microphones arranged around the belt. The design idea is that the microphone closest to a sound source will receive the highest signal amplitude, since received sound pressure (p) is inversely related to the distance (r) from the sound source. p ~ 1/r By comparing the microphone signals and finding the highest sampled amplitude, we can effectively localize sound and alert the user of the direction, using common cellphone type motors. To improve functionality, other features have been included. These features allow the Vibraid to filter out noise or unwanted signals as well as function in different sound level environments. Finally, the strength of the motors can be changed for comfort. Mike Spiros Andy Leo Prof. Janaswamy

Cost Input Block Processing Block DevelopmentProduction The input block is responsible for picking up all sounds which surround the user. It consists of the four unidirectional microphones, which are biased up and amplified for suitable processing by the Arduino. The input block also implements an envelope detector circuit that rectifies the AC sound signal and produces a DC signal that represents the average “sound pressure level.” This can be used as a comparison measure of sounds in the processing block. The Arduino is the core of the device. Taking the AC sound signal as an input, it implements an optimized Fast Fourier Transform to determine the fundamental frequency of the sound. If the frequency falls within the user-selected frequency band, the DC sound-pressure-level signals are then compared with each other, to determine the highest average signal sound pressure level among all four microphones. If this highest average exceeds a user- set threshold, the corresponding motor that is associated with the direction of the microphone that received the strongest sound is activated. The interface block provides the user with a set of switches and knobs which allows them to customize the device to meet specific needs. A sensitivity knob allows the user to set thresholds for which minimum sound can be detected. A motor strength switch will toggle the vibration strength of the motors around the user’s waist, to meet the user’s sensitivity preferences. The user can customize the device to hone in on specific sounds, through the three filter switches. These switches, which correspond to low, band, and high pass filters, can be combined to create unique combinations of filters. Interface Block Output Block The output block consists of four motors. These motors correspond to four different quadrants from which sound can be distinguished between. The processing block will send incoming signals to the output block and activate the motors with an intensity that the user selected. The user will feel the motor’s vibration in a specific quadrant, and be alerted of a sound source located in said direction. Target Sound Frequencies (TSF) SoundsFrequencyVibraid Filter Band Baby Cries~3500HzHigh Fire Alarm~1000HzHigh Car Horn~700HzHigh Emergency vehicle siren ~1000HzHigh Human Voice ~ HzLow + Mid Wind~100HzLow Low: 100 – 300Hz Mid: 300 – 600HzHigh: 600 – 7000Hz Envelope of signal whose average magnitude is compared to that of other microphone inputs Raw sound signal that is used for frequency analysis