M. Smith, M. Heisie*, L.Wolfram †, M. Aebischer †, E. Marasco University of Calgary, Canada, *University of Toronto, Canada, † Ecole d’Ingeniers et d’architectes de Fribourg, Switzerland SSSSH! – Low-cost, Noise Cancelling Solutions for Noise Pollution Issues in the Urban Home

Ranchland’s Hum and other Urban annoyances Noise pollution in an urban environment can be problematic. Obvious problems to solve are (A) Locating the noise source (B) Negotiating to have it stopped. (C) Helping the home owner cope with the noise pollution until solutions for (A) and (B) have been found. This talk is about investigation of whether ‘coping’ can be assisted using a simple noise cancellation approach with a cost of under $500 plus stuff already in a house 2 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING

Embedded Systems Courses at University of Calgary Third year ENCM511 Interfacing with the real world. Fourth year ENCM515 Signal processing issues combined with learning how to write code for ‘real time operation’. REAL TIME means providing results now, and not once we have got back to the office. Industry sponsored 4 th year team design projects SHARC EVALUATION BOARD Teaching equipment provided through Analog Devices 3 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING

SSSSH! --- SHARC SOUND SUPPRESSION SYSTEM for the HOME 4 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING

Key elements Pick up nuisance sound through microphone array Analyze the nuisance sound Generate a noise cancellation solution Use home theatre system as amplifiers to reduce cost Already exists – therefore people likely to try it Flexible system -- Can also provide Quantitative analysis metrics to support nuisance claims Home tutoring for musicians (Presented at an earlier talk) etc 5 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING

Theory – How should it work? Design of an Electronic Muffler - A DSP Based Capstone Design Project PDF 6 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING

Theory – How should it work? WHAT HAPPENS WITH “REAL NOISE SOURCE” 7 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING

Investigation configuration UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING 8 LAP-TOP AUDIOCITY – AUDIO RECORDING CUSTOM GUI – STORE ANALYSIS RESULTS USE LAP-TOP AUDIO TO BOOST MICROPHONE SIGNAL SHARC PROVIDES REAL-TIME ANALYSIS LEDS INDICATE FREQUENCIES PRESENT CORRECTIVE AUDIO OUT ANALYSIS RESULTS AUDIO IN

Problems with ‘distance effects’ and ‘extended sources’ 9 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING NEIGHBOUR’S ALPHINE HORN

Frequency dependence of the problem Works for 64 Hz but not 128 Hz 10 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING

Lets STOP looking for the perfect solution Choose a series of useful target situations In the bedroom and generally round-and-about in the house My Ranchland’s Hum Experience – distant sound source? Low D# (around 40 Hz) – distant refrigerator Annoyance level out of 10. Dripping tap in the bath room However – once noticed would be enough to keep me awake – especially whenever sound characteristics changed Assume obvious solutions tried Furnace summer fan – white noise source Relocate sleeping location to a ‘null’ in a standing wave? 11 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING

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SHARC BASED SSSH! UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING 13 SHARC ADSP system Designed as a HOME THEATRE demonstration system Specialized hardware for high speed DSP (digital signal processing) calculations Specialized DSP language extensions for high speed real time calculations using C language Can handle 4 audio input signals Needs help to handle microphones -- home audio system / lap-top Can generate 8 speaker signals directly Speakers probably inside house unless protecting a community (from wind farm noise)

Real Life problems to cope with! Are virtual speakers a help or a hindrance? UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING 14

Real life distance effects 15 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING CLOSE SPEAKERS PRODUCE SPHERICAL WAVEFRONTS

This configuration External microphones to capture true noise characteristics In room speakers In-room sound microphones to check on compensation Complicated DSP algorithms probably need to be developed to handle sound reflections, spherical sound waves Must work for on both sides of the bed Look for simpler solution that remove all the problems! Multiple microphone ear inserts + earpiece ANC 16 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING

This technology under development BUT do we have to wait? Normal hearing aid Dual micro-phones – single speaker Problem How do you keep the speaker in place in the ear? Plastic inserts to hold speaker – but which block low frequency sound Compensate by boosting blocked low frequency signals by changing hearing aid characteristics Lets play with this idea Completely block all sounds with an ear-mold (essentially ear-plug) Then reintroduce normal sounds using a hearing aid speaker This is ‘sort of’ already done with ‘electronic hunter’ protection devices – WALKER GAME EARS 17 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING

wkrs_bte_dighd_elite_01.html 18 UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING

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Discussion and Conclusion UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING 20 Use active sound suppression – GAME EARS or equivalent Fits directly into ear – blocks Hum but enables normal hearing Useable in bed or walking around the house Cheap when compared to high end hearing aids $39 to $500 / $600 compared to $3500 per ear) Use SSSSH! Embedded system device more for analysis and providing support for claims Prototype already available Investigate moving application to cell phones and lap-tops

Where to next? UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING 21 Industrial suggested (sponsored) 4 yr Undergraduate Engineering team design project NSERC (Natural Sciences and Engineering Research Council) Industrial summer student research project Industrial M. Sc. or Ph. D. Scholarships For more information to UCALGARY.CA

Acknowledgements UCALGARY.CA SCHULICH SCHOOL OF ENGINEERING 22 Financial support provided through Industrial Collaborative Research and Development grant between NSERC (Canada), Analog Devices (US and Canada), CDL Systems (Calgary, Canada), Ecole d’Ingeniers et d’architectes de Fribourg, Switzerland. Additional financial support from the University of Calgary. Richard Patching, Patching Associates, Calgary