自己課浸泡營713聽力

TPO7Lecture2題目請(qǐng)務(wù)必先做一遍，對(duì)選項(xiàng)有個(gè)了解whatisthelecturemainlyHowanimalsemitultrasonicHowbatsuseacousticalAcomparisonofecholocationandVariationsamongbatsintheuseofwhydoestheprofessordecideNOTtoaddmoreinformationtothediagramonthe細(xì)節(jié)態(tài)度ShewantsstudentstocompletethediagramthemselvesasanSheneedstolookupsomeinformationinordertocompletethediagram TheadditionalinformationisnotrelevanttothetopicthatshewantstodiscussStudentsalreadyhavetheadditionalinformationintheirAccordingtotheprofessorwhataretwowaysinwhichamothmightreactwhenitdetectsthepresenceofabat?（8細(xì)節(jié)）Clickon2Themothmightstopbeatingits Themothmightemithigh-frequencyThemothmightleavethe ThemothmightchangeitscolortomatchitsWhatsurprisinginformationdidarecentexperimentrevealaboutlesserspear-nosed細(xì)節(jié)TheyfilteroutechoesfromsometypesofTheycanyzeechoesfromstationaryobjectswithcomplexThey yze"jagged"They yzeechoesfromcertaintypesofsmallmovingAccordingtotheprofessor,whydoesapinetreeproducea"smooth"echo?（12細(xì)節(jié)BecauseithasasmoothBecauseithaslargebranchesspacedatregularBecauseithasmanysmall,denselypackedBecauseitremainsstationaryinalltypesofWhydoestheprofessorsaythis()（重聽ToansweraquestionthatCarolTocorrectastatementthatCarolTopraiseCarolforanexamplethatsheTogiveanexampleofaprinciplethatCarolListentopartofalectureinaBiologyPro:So,thatishowelephantsuseinfrasound.Now,let’stalkabouttheotherendoftheacousticalspectrum,soundthatistoohighforhumanstohear---ultrasound.Ultrasoundisusedbymanyanimalsthatdetectandsomeofthemsendoutveryhighfrequencysounds.So,whatisagoodexample?Yes?Carol.Carol:Well,bats,sincetheyareallblind,batshavetousesoundfor,youknow,tokeepfromflyingintothings.Pro:Thatisecholocation.Echolocationisprettyself-exnatory;usingechoes,reflectedsoundwavestolocatethings.AsCarolsaid,batsuseitfornavigationandorientation.Andwhatelse?Mike:Well,findingfoodisalwaysimportant,andIguess ingfoodforotherPro:Right,onbothcounts.Avoidingotherpredators,andlocatingprey,typicallyinsectsthatflyaroundatnight.NowbeforeIgoon,letmejustrespondtosomethingCarolwassaying---thisideathatbatsareblind.Actually,therearesomespeciesofbats,theonesthatdon’tuseecholocationthatdorelyontheirvisionfornavigation,butitistruethatformanybats,theirvisionistooweaktocounton.Ok,soquicksummaryofhowecholocationworks.Thebatemitstheseultrasonicpulses,veryhighpitchsoundwavesthatwecannothear.Andthen,theyyzetheechoes,howthewavesbounceback.Here,letmefinishthisdiagramIstartedbeforeclass.Sothebatsendsoutthesepulses,veryfocusedburstsofsound,andechoesbounceback.Youknow,Idon’tthinkIneedtodrawontheechoes,yourreadingassignmentforthenextclass;ithasadiagramthatshowsthisveryclearly.引人注意+否定So,anyway,asIweresaying,byyzingtheseechoes,thebatcandetermine,say,ifthereiswallinacavethatitneedstoavoid,andhowfarawayitis.Anotherthingitusesultrasoundtodetectisthesizeandshapeofobjects.Forexample,oneechotheyquicklyidentifyistheonetheyassociatewithamoth,whichiscommonpreyforabat,particularlyamothbeatingitswings.However,mothhappenedtohaveamajoradvantageovermostotherinsects.Theycandetectultrasound;thismeansthatwhenabatapproaches,themothcandetectthebat’spresence.So,ithastimetoescapetosafetyorelsetheycanjustremainmotionlessSincewhentheystopbeatingtheirwings,they’dbemuchharderforthebattodistinguishfrom,oh…aleaforsomeotherobject.因果并列Now,wehavetendedtounderestimatejusthowsophisticatedtheabilitiesofanimalsthatuseultrasoundare.Infact,wekindofassumedthattheywerefilteringalotout,thewayasophisticatedradarsystemcanignoreechoesfromstationaryobjectsontheground.Radardoesthistoremovegroundclutter,informationabouthillsorbuildingsthatitdoesn’tneed.Butbats,wethoughttheywerefilteringoutthiskindofinformation,becausetheysimplycouldn’tyzeit.But,itlooksasifwewerewrong.Recentlytherewasthisexperimentwithtreesandaspeciesofbats.Abatcalled:thelesserspearnosedNow,atreeshouldbeahugeacousticalchallengeforabat,right?Imeanit’sgotallkindsofsurfaceswithdifferentshapesandangles.So,well,theechoesfromatreearegoingtoamassofchaoticacousticreflections,right,notliketheechofromamoth.So,wethoughtforalongtimethatbatsstoptheirevaluationatsimplythatisatree.Yet,itturnsoutthatbatsoratleastthisparticularspecies,cannotonlylthatisatree,butcanalsodistinguishbetween,say,apinetree,andadeciduoustree,likeamapleoroaktree,justbytheirleaves.AndwhenIsay,leaves,ImeanpineneedlestooAnyideasonhowitwouldknowthat?（轉(zhuǎn)折遞進(jìn)+舉例）Stu:Well,likewiththemoth,coulditbetheirPro:Youareontherighttrack---itisactuallytheechoofalltheleavesaswholethatmatters.Now,think,apinetreewithallthoselittledenselypackedneedles.Thoseproducealargenumberoffaintreflectionsinwhat’s...what’scalleda...asmoothecho.Thewavef