Senior Design 2012 Tom Blanford Eric Nolan Michael Sizemore Sara Taylor Mark Wurzelbacher University of Notre Dame

Current Products: Traditional Isolation Headphones

SilentRave’s Solution: Variable Isolation Headphones Pass-Thru Isolation

Pass-Thru Isolation x x

Modes & Uses Ambient Mix in level of external audio (microphone signal) Remain aware of surroundings Total Isolation Increase volume as external audio levels increase Running in safe but dynamically noisy area Conversation When sizeable level of human voice (20 Hz – 20 kHz) is detected, decrease music volume, boost external audio If someone close to you talks, don’t fumble with headphones, just respond!

Features! Stereo imaging Compression and limiting for higher volumes Equalization of microphone and headphones Bypass mode for failure state

DSP Diagram Mic IN Music INProgram Control Audio OUT

Signal Paths Stereo ADC I2CI2C Digital IN Stereo DAC External ADC Music Mic L Mic R EEPROM Stereo OUT 8-bit A/D Slider switch, buttons

ADC Microphone input in DSP Power switch 3-way switch EEPROM Music in Music out Volume Control AC Adapter Reset button

Microphone Board Board Schematic

Future Enhancements Reduced size and weight of case to be more suitable for a running device New modes programmed for different scenarios Adjustable thresholds through user input and/or ambient noise monitoring