Kyle Desrosiers (ME)- Team Lead Brad Fiedler (EE) Greg Wodzicki (EE) Chris VanWagenen (EE) George Slack- Faculty Guide P ACTIVE NOISE CANCELLATION Acknowledgements: Cenco Physics Texas Instruments

PROJECT DESCRIPTION This project aims to attenuate sound level output of a given source using an Active Noise Cancellation system (ANC). First of a series of projects ultimately targeting attenuation of Internal Combustion Engine.

KEY CUSTOMER NEEDS Prove concept of sound attenuation via Active Cancellation Demonstrate technical challenges limitations of ANC ANC system fully functional to work on a given input

KEY ENGINEERING SPECS Noise reduction- Source only vs ANC system on Target: >6dB Ideal conditions: ~17dB Effective Frequency range Ideal: 20-20k Hz (Human Auditory Range) Actual: Hz Processing time Ideal: 0.5 ms Actual: Unknown Speaker Output Level ~100dB

CONCEPT SUMMARY Sound Waves: Propagation of compression and rarefaction through air Source:

SUPER POSITIONING OF WAVES In Phase Out of Phase

SYSTEM ARCHITECTURE Microphones: Input Signal, Error Signal Power Amplifier: Behringer EPQ1200 Speaker: Goldwood GW-210/8 DSP: TAS3108EVM2 Eval Kit C5505 DSP Eval Kit

DESIGN SUMMARY System Spec’d for Lawn Mower Engine Wye Configuration, Dipole Configuration Speakers: 10in, 110 Watt RMS 86.5 dB Sound Level output Hz Amp 2 x 320 Watts at 8 Ohms

DESIGN SUMMARY Microphone Typical Frequency Response Cheap For Initial Testing DSP TAS3108EVM2 Eval Kit C5505 DSP Eval Kit

DSP TAS3108EVM2 Eval Kit Sampling Rate: 192 kHz Programmable in Assembly or GUI Interface 8 Inputs/outputs C5505 DSP Eval Kit Sampling Rate: 48 kHz Programmable in C++ TI Support 2 Inputs/Outputs

ALGORITHM

TESTING/RESULTS Matlab Simulation

TESTING/RESULTS Test Setups Conducted Straight Inverted Signal, Equal Path Length Wye Dipole Box

TESTING/RESULTS 4in Pipe, Wye

TESTING/RESULTS 4in Pipe, Dipole Lawn Mower Sound Wave 8dB Reduction

TESTING/RESULTS 6in, Wye Connection Complex Sounds Dependent on sound Achieved 8dB reduction

TESTING/RESULTS Using Microphones and DSP Max Reduction achieved: 3dB Feedback through mics limited test range Testing conducted at low sound levels

SUCCESSES AND FAILURES Successes Proof of concept Geometry, superposition Pure tones Cancellation of low frequencies with inversion

SUCCESSES AND FAILURES Failures Programming original DSP Programming second DSP, fine tuning Microphone Feedback, Clipping Unable to implement on non electrical sound source

FUTURE WORK Testing 6 inch dipole setup Back pressure with system in use Algorithm debugged New microphones Eliminate feedback/clipping issue System downsized, optimized Application to mechanical sound source

SUGGESTIONS Computer engineer Better knowledge of programming Increased budget Microphones with proper range, sensitivity, heat properties More expert advice/input