聲導抗基礎知識

聲導抗基礎知識Soundtravel聲音傳導22020/11/30Gettingsoundintoadifferentmedium

聲音在不同媒介中的傳導Mostofthesoundenergyisreflectedwhenconfrontingaanothermedium...大部分聲能在臨界面處被反射回來…becausedifferentmediaaremoreorlesseasytobringintomotion(impedance)因為不同媒介的聲阻抗是不同的32020/11/30Theroleofthemiddleear中耳的作用

42020/11/30TheOssicles聽小骨Malleus錘骨Incus砧骨Stapes鐙骨Threesmallbonesformingachainbetweenthetympanicmembraneandtheinnerear聽骨鏈位于鼓膜和內耳之間，由3塊聽小骨組成Airbornesoundwaveenergybecomesmechanicalvibration空氣傳導的聲波能量轉換為機械振動Compensatesfortheair-fluidimpedancedifference補償氣液相不同媒介的導抗差52020/11/30TheMiddleearanatomy中耳解剖AirAirAirpressuremustbenearequalonbothsidesoftheeardruminordertooptimisemobilityofthewholesystem應使鼓膜兩側氣壓接近，從而保證中耳傳聲系統(tǒng)的最佳活動性TheEustachiantube(ET)ventilatesthemiddleearandallowspressureequalisation咽鼓管是中耳的通氣管道，可保證中耳氣壓平衡TheETopenswhenswallowingoryawning吞咽和打哈欠時咽鼓管開放Innerearfluids內淋巴62020/11/30Gettingsoundintoadifferentmedium

聲音在不同媒介中的傳導The“stiletto”principle:圓錐效應Forceiscollectedoveralargerareaandfocusedonasmallerarea(B)作用力在錐底收集后聚焦到錐尖72020/11/30Howdowetestthemiddleear?

如何檢測中耳功能82020/11/30中耳測試精密的中耳系統(tǒng)高精度的測試高質量控制系統(tǒng)92020/11/30Partoftheprobetoneisreflected,andsomeisadmittedintothemiddleear一部分探測音被反射回來，另一部分則進入中耳Theadmittanceiscontinuouslymeasuredbyamicrophone聲導納通過麥克風持續(xù)測量計算出來Admittance-lettingthesoundwavein

聲導納－將聲波導入102020/11/30鼓室圖中耳–勁度TPP(=MEP?)AdmittancePressure112020/11/30Tympanometry鼓室聲導抗Admittance-200daPa200daPa0EarcanalpressureAdmittance聲導納-200daPa200daPa0Earcanalpressure外耳道壓強1&3:Pressurestiffensthetympanicmembranesotheprobetonebouncesback,andthesoundlevelinthemiddleeardecreases1和3：大壓強使鼓膜僵硬從而探測音多被反彈回來，進入中耳的聲能減少2:Whenpressureisequalonbothsides,thesoundlevelinthemiddleearisatmaximum2：鼓膜兩側壓力相等時傳入中耳的聲能最大

123122020/11/30TheTympanogramcurve,ECVandTPP

鼓室導抗圖形，等效外耳道容積和峰壓點TheTPPapproximatesthemiddleearpressure峰壓點近似于鼓膜內側的中耳壓力ECVTotalAdmittanceoftheearcanalandthemiddleear外耳道和中耳的聲導納總值TPPPressuresweepThe226Hzadmittanceoftheairintheearcanalisdirectlyproportionaltothevolumeofthatair.ThatgivesustheEquivalentEarCanalVolume,ECV以226Hz為探測音，測試探頭與鼓膜之間的空氣導納值為外耳道容積，即等效外耳道容積132020/11/30ECVTotalAdmittanceSATPPSATPPTheTympanogramcurveandbaselinecompensation鼓室導抗圖形和基線補償SubtractionoftheECVcontributiongivesusabaselinecompensatedtympanogram去除外耳道容積成分后的鼓室圖稱為基線補償鼓室導抗圖PeakadmittancebecomesStaticAdmittance,SA該圖峰值處的聲導納稱為靜態(tài)聲導納(SA)TheSAistheadmittanceofthemiddleearalone.Nowwecanusethenormativedata!SA等于中耳的聲導納值142020/11/30-2002000TypeAd:OssiculardiscontinuityoragerelatedhypermobilityAd型：聽骨鏈中斷或鼓膜松弛-2002000TypeA:NormalA型：正常-2002000TypeB:“Flat”-EffusionorperforatedeardrumdependingonECVvalueB型：平坦型。鼓室積液或鼓膜穿孔，根據(jù)ECV值區(qū)分-2002000TypeAs:PossibleeffusionorotosclerosisAs型：鼓室積液可能或耳硬化癥-2002000TypeC:AbnormalpressureC型：負壓型TheTympanogramcurveclassification,Type鼓室導抗圖形分類152020/11/30SATWSA/2PressureAdmittanceTheTympanogramcurveandTympanometricWidth

鼓室導抗圖形與鼓室圖寬度（TW）TympanometricWidthquantifythesteepnessofthetympanogramTW決定鼓室導抗圖的坡度Normativedataexistfordifferentagegroups不同年齡組標準化值不同TWandSAarethecriteriausedintheASHAtympanometricscreeningprotocol美國社會衛(wèi)生學會的鼓室聲導抗篩查方案把TW和SA作為診斷指標162020/11/30226Hz:Differentconfigurationsoftympanometricresults

226Hz鼓室聲導抗測試結果與疾病的關系Tympanometryisaninvaluablediagnostictoolwhencombinedwithotheraudiologicaltests鼓室聲導抗與其它聽力學測試結合是不可替代的診斷工具疾病早期中耳積液中耳積液聽骨鏈中斷鼓膜病變耳硬化癥錘骨固定咽鼓管阻塞鼓膜置管鼓膜穿孔耵聹栓塞、探頭叩堵塞172020/11/30Thetwomiddleearmuscles中耳肌121:Tensormuscle鼓膜張肌2:StapediusMuscle鐙骨肌Themusclesarebelievedtostabilisethemechanicalsystemandprotectthecochleafromexcessivelowfrequencyvibration中耳肌可穩(wěn)定中耳機械系統(tǒng)，并保護耳蝸免受低頻強聲損傷182020/11/30TheAcousticReflex聲反射Loudsoundsmakethestapediusmusclecontract.Thismakesthemiddleearsystemstiffer...強聲刺激可使鐙骨肌收縮，從而增加中耳傳聲系統(tǒng)的勁度…andlesslowfrequencysoundcangetthroughthemiddleear因而進入中耳的低頻聲波減少192020/11/30Stapediusmusclecontrolledbyfacialnerve(CNVII)

鐙骨肌由第七對顱神經(jīng)－面神經(jīng)支配Networkinbrainstemconsistsofipsilateralandcontralateralpaths

腦干層面由同側和對側神經(jīng)通路組成Reflexactivatedonbothears,evenwhenstimulationonlyoccursinoneear

一側耳受到刺激時，雙側鐙骨肌都會收縮Comparisonofipsilateralvs.contralateralacousticreflexeshelpstodeterminesiteoflesion

對比同側和對側聲反射有助于判斷病變部位TheMiddleear-Immittancetests中耳聲導納測試Acousticreflexthreshold聲反射閾202020/11/30聲反射AdmittanceTimeDeflection0.02蹬骨肌212020/11/300.000.0280dBHL0.000.0285dBHL0.000.0295dBHL0.000.0290dBHLDeflectioncriterion聲導納偏移標準Itisusefultostudythegrowthwithintensitytoconfirmareflexthreshold繼續(xù)增加聲強觀察偏移變化有助于進一步明確聲反射閾?!AcousticReflexThresholds聲反射閾Loudstimuliarepresented,whilsttheadmittanceismeasured強聲刺激出現(xiàn)時，可測試出聲導納值的變化222020/11/30聲反射測試–高精度的挑戰(zhàn)鼓膜處壓力為TPP值時中耳蹬骨肌反射狀況最佳正確的聲反射是刺激音引起導納在TPP處的變化耳道或中耳壓力的改變導致錯誤的聲反射對于鼓膜活動度過大可進行TPP補償232020/11/30Threshold+10dB,10secondsstimulustime聲反射閾上10dB給聲，刺激時程10s0510secondsAdmittancechangeHalf-LifeTime(HLT),thetimeafterstimulusonsetwhentheadmittancedeflectionhasdecreasedby50%.半衰期是指聲反射振幅減少50％的時程Ahalf-lifetimevalue<5secondsisindicativeoftumour半衰期小于5秒提示蝸后病變，常見的疾病是聽神經(jīng)瘤Noreflexdecaypresent陰性AdmittancechangeMax50%ofMaxHLT0510secondsReflexdecaypresent!陽性AcousticReflexDecay聲反射衰減242020/11/30Thereflexshouldbeactivatedinbothearsevenifstimulatedinonlyoneear單耳刺激聲可激活雙耳聲反射Theuppernormalintensitylimitforreflexthresholdsinadultsis95-100dBHL正常成人聲反射閾上限是95－100dBHLReflexthresholdscannotbedeterminedifthereisaproblemwiththemiddleear

中耳疾病時不能測出聲反射閾BroadBandNoiseprovokesareflexatabout10-15dBlowerthanpuretonestimuli寬帶噪聲聲反射閾較純音刺激聲低10－15dBDeterminestypeofhearinglosswhencomparedwiththeaudiogram聲反射閾與聽力圖比較可幫助判斷耳聾類型Decayswithneuralfatigue(typically8thnervetumour)

衰減提示聽神經(jīng)疲勞，是聽神經(jīng)腫瘤的典型表現(xiàn)AcousticReflexfeatures聲反射特征252020/11/30DifferentconfigurationsofAcousticReflexresults聲反射結果與疾病的關系Usingthiskindoftablemakesreflexinterpretationeasier使用該表格有助于判斷聲反射的臨床意義病變部位/患耳中耳/右中耳/左耳蝸/右耳蝸/左聽神經(jīng)/右聽神經(jīng)/左面神經(jīng)/右面神經(jīng)/左腦干/右腦干/左腦干/中線262020/11/30226Hzprobetone:Normaltympanograminabnormalear!226Hz探測音：異常中耳顯示正常鼓室導抗圖Tympanometryininfantsyoungerthan4-7months4－7個月以下嬰兒的鼓室聲導抗226HzprobetoneTheinfantouterandmiddleearsarestilldeveloping,anddonotvibratewithsoundthesamewayadultearsdo.嬰兒外耳和中耳正處于發(fā)育期，與成人的聲波振動方式不同Use1000Hzprobetoneininfants推薦使用1KHz探測音272020/11/30Tympanometryininfants嬰兒鼓室聲導抗1000Hztympanometryclearlyindicatesabnormalmiddleearfunction!1kHz鼓室聲導抗明確顯示中耳功能異常Normal226Hztympanogramsforbothears!226Hz鼓室聲導抗顯示雙耳正常Acousticreflexesconfirmahealthyrightsidemiddleear.聲反射證實右側中耳功能正常282020/11/30HoweasilycanImovethisme－chanicalsystem?怎樣輕而易舉的推動這個機械系統(tǒng)？Traditionaladmittancemagnitudetympanometry

傳統(tǒng)鼓室聲導抗中聲導納的成分292020/11/30B/Gcomponenttympanogram聲納/聲導成分鼓室導抗圖B:Susceptance聲納G:Conductance聲導302020/11/30NowIcanseenotonlyhoweasilyIcanmovethesystem,butIcanactuallyfindoutwhy!現(xiàn)在我不僅能輕而易舉的推動它，而且還明白了其中的原因！SusceptanceandConductancemagnitude

tympanometry聲導與聲納312020/11/30TraditionalbaselinecompensationEarcanaleffectat+200daPaCCSAisn