SSSSH Lowcost Noise Cancelling Solutions for Noise Pollution

SSSSH! – Low-cost, Noise Cancelling Solutions for Noise Pollution Issues in the Urban Home 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

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. 2 This talk is about investigation of whether ‘coping’ can@ UCALGARY. CA be assisted using a simple noise SMITHMR SCHULICH SCHOOL OF ENGINEERING cancellation approach with a cost of under $500

Embedded Systems Courses at University of Calgary � Third year ENCM 511 Interfacing with the real world. � Fourth year ENCM 515 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 SMITHMR @ UCALGARY. CA SCHULICH 3 year team design SCHOOL OF ENGINEERING projects SHARC EVALUATION BOARD Teaching equipment provided through Analog Devices

SUPPRESSION SYSTEM for the HOME 4 SMITHMR @ 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 5 claims SMITHMR @ UCALGARY. CA SCHULICH SCHOOL OF �Home tutoring for musicians (Presented at an earlier ENGINEERING

Theory – How should it work? Design of an Electronic Muffler - A DSP Based Capstone Design Project http: //www. usna. edu/Users/weapsys/avramov/education/AC_2001 Paper SMITHMR @ UCALGARY. CA SCHULICH SCHOOL OF 214 muffler. PDF 6 ENGINEERING

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

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

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

Frequency dependence of the problem Works for C @ 64 Hz but not C @ 128 Hz 10 SMITHMR @ 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-about in the house �My Ranchland’s Hum Experience – distant sound source? �Low D# (around 40 Hz) – distant refrigerator �Annoyance level --- 1 out of 10. Dripping tap in the bath room �However – once noticed would be enough to 11 keep me awake – especially whenever sound characteristics changed �Assume obvious solutions SMITHMR @ UCALGARY. CA SCHULICH SCHOOL tried OF �Furnace summer fan – white noise source ENGINEERING

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SHARC BASED SSSH! � SHARC ADSP-21469 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) 13 SMITHMR @ UCALGARY. CA SCHULICH SCHOOL OF ENGINEERING

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

Real life distance effects 15 CLOSE SPEAKERS PRODUCE SMITHMR @ UCALGARY. CA SCHULICH SCHOOLSPHERICAL OF WAVEFRONTS ENGINEERING

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! earpiece ANC 16 Multiple microphone ear inserts + SMITHMR @ 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’ 17 protection devices – WALKER GAME EARS SMITHMR @ UCALGARY. CA SCHULICH SCHOOL OF ENGINEERING

www. walkersgameear. com/wkrs_pro ducts/wkrs_bte_dighd_elite_01. html 18 SMITHMR @ UCALGARY. CA SCHULICH SCHOOL OF ENGINEERING

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Discussion and Conclusion 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) 20 Use SSSSH! Embedded system device more for analysis and providing support for claims �Prototype already available SMITHMR @ UCALGARY. CA SCHULICH SCHOOL OF ENGINEERING �Investigate moving application to cell phones and

Where to next? �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 email to SMITHMR @ UCALGARY. CA 21 SMITHMR @ UCALGARY. CA SCHULICH SCHOOL OF ENGINEERING

Acknowledgements �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 22 SMITHMR @ UCALGARY. CA SCHULICH SCHOOL OF ENGINEERING