Mathematics and Society - OS X Lion Server

"' ':,~'~:,':>' ," ..~ '. ,": ~ ; ./ / ." ':,I I • "Sound Levels and Human ResponseHearingEffectsConversationalRelationships(Carrier DeckJet OperationJet Takeoll(200 feet)DiscothequeAuto Horn (3 teet)Riveting MachineJet TakaoH(2,000 leet)Garbage TruckN.Y. SubwayStationHeavy Truck(50 feet)Pneumatic Drill(50 feet)Alarm ClockFreight Train(50 feel)Freeway TraHie(50 teel)Air ConditioningUnit (20 leel)Light Auto Traffic(100 feet)Living RoomBedroomlibrarySoft Whisper(15 fe~t)BroadcastingStudioConversation, 12 fl.An introduction to decibelscould follow work with noise,particularly if you can borrow anoise level meter. Studentscould then experience soundswith their associated decibellevels. Have students find thelevels of noise around school;classroom, hallway, cafeteria,bandroom, library.Several activities on soundmay be found in the MATHEMATICSAND MUSIC unit in the resourceMathematics in Science andSociety.The decibel unit is namedafter Alexander Bell; a decibelis 0.1 of a bel. The definition (of the unit is too advanced for .most middle schoolers, but onepoint should be made: A decibellevel of 40, say, is not twiceas intense as a level of 20decibels; it is 100 times asintense. Since loud sounds areoften quite intense, it is perhapsnot too misleading to saythat the decibel level measuresthe loudness of sounds.Here are some other notes onsound and decibel levels:Chart from Noise Pollution, Environmental ProtectionQuiet(!) classroom--20; cityAgencytraffic--75; Air Force recommendedmaximum--82; inside acity bus--85; sports car--86; screaming child--92; pushing a lawn mower--96;outboardmotor--l02; motorcycle--lll; kills mice--160; rocket engine--180. Eardrums can break atfrom 120-130 decibels.218Noise can make it hard to think. Some schools near airports have had to close becauseof this. Some office buildings in large cities use sound-proof glass to reducenoise. Besides causing hearing loss, noise can increase the stress on people, make themshort-tempered and even lead to high blood pressure. It is estimated that some workers (spend 15% of their energy "fighting" noise; some jobs require ear plugs. Students may .know that loud rock music has damaged many young people's ears. Students could be askedto suggest ways to reduce noise pollution.