Physics 1240 1/31/06Today: Human ear and hearingNext time: Loudness versus pitch, perception of soundOutline- Exam I – “the curve”- SIL (dBs) versus intensity (W/m2)- The human ear – an amazing detector!- The function of the outer ear- The function of the middle ear- The function of the inner earCT11.1 (Exam Problem 20.)A sound wave has a compression of 1.001 atm. What is the total air pressure at the rarefactions in atmospheres?A) 0.001 atmB) -0.001 atmC) 10,100 N/m2D) 0.99 atmE) none of the aboveDistribution of exam scores0510152025243240444852566064687276808488929610010488 A76 B72 B-68 C+60 C52 D(48 and below F)Median 72Topics you need to know for Exam II- SIL(dB) and Intenstiy (W/m2)- The human ear- Loudness, Loudness versus pitch- The keyboard, musical notes and major scale- Musical intervalsCT11.2 (a problem we took off of Exam I)The volume on an audio amplifier is increased so that the SIL is increased 30dB. How much of an increase is that in sound intensity (W/m2)?A) a factor of 30B) a factor of 100C) a factor of 300D) a factor of 1000E) none of the aboveCT11.3 ( a problem I found on last year’s Exam II )To get the sound intensity of 0.1 W/m2, what sound intensity level (SIL) must you have?a. 90 dBb. 100 dBc. 110 dBd. 120 dBPut table on your note page!The Anatomy of the Human EarGraphics from www.vimm.it/cochlea/(F. Mammano and R. Nobili)outer ear, middle ear, inner earPinnaAuditory CanalImportant parts – cochlea is shown unrolledNeed to knowPinna, auditory canalEar drum, ossicles: Hammer, anvil stirrupOval window, circular windowBasilar membrane, hair cells, auditory nerveThe Cochlea – actual shapeAuditory nerveBasilar membraneOrgan of corti(hair cells)The Cochlea – cross-section or sliceHair cellsBasilar membraneBasic mechanics of the earThe cochlea as a Frequency sensorCT11.4When different regions of the basilar membrane vibrate what information does this provide to your auditory nerve?A) differences is intensityB) differences in frequencyC) loudness protection patternsD) both A) and C)E) none of the
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