1Physics 1201Speed of Sound Different in different materials v = 331 m/s in air at 00C and at 1 atm temperature dependence v = (331 +0.60 T) m/sPhysics 1202Characteristics of Sound Loudness intensity; energy per area per time Pitch high or low frequency Audible range of human ear 20 Hz to 20,000 HzPhysics 1203Decibels Intensity of sound is measured in decibels range of 1012 between intensity of quietestand loudest sounds we can hear ear hears on logarithmic scale decibel - measure of intensityPhysics 1204Intensity2Physics 1205Human EarPhysics 1206Frequency Response of EarPhysics 1207Sources of sound string instruments sound amplified sounding box sounding boardPhysics 1208Ch 12: Problem 78 A highway overpass wasobserved to resonate as onefull loop when a smallearthquake shook theground vertically at 4.0 Hz.The highway department puta support at the center ofthe overpass, anchoring it tothe ground. What resonantfrequency would you nowexpect for the overpass?Earthquakes rarely dosignificant shaking above 5or 6 Hz. Did themodifications do any good?3Physics 1209Sources of Sound:Wind InstrumentsPhysics 12010Closed at one endPhysics 12011Quality of SoundPhysics 12012Interference & Beatsfbeats = fA - fB4Physics 12013Doppler EffecthigherfrequencylowerfrequencyPhysics 12014Doppler Effect v = speed of wave vo = speed of observer vs = speed of source f0 = emitted frequency f’ = observed frequency f’ > f0 s and o approaching f’ < f0 s and o recedingPhysics 12015Sonic BoomPhysics 12016Ultrasound Imagingcolor reflects strengthof echodelay of echo indicatesdistance to