聲導(dǎo)抗基礎(chǔ)知識(shí)

1、Sound travel 聲音傳導(dǎo)聲音傳導(dǎo) Getting sound into a different medium 聲音在不同媒介中的傳導(dǎo)聲音在不同媒介中的傳導(dǎo) Most of the sound energy is reflected when confronting a another medium. 大部分聲能在臨界面處被反射回來 because different media are more or less easy to bring into motion (impedance) 因?yàn)椴煌浇榈穆曌杩故遣煌?The role of the middle ear 中耳的作用中耳

2、的作用 The Ossicles 聽小骨聽小骨Malleus 錘骨 Incus 砧骨 Stapes 鐙骨 Three small bones forming a chain between the tympanic membrane and the inner ear 聽骨鏈位于鼓膜和內(nèi)耳之間，由3塊聽小骨組成 Airborne sound wave energy becomes mechanical vibration 空氣傳導(dǎo)的聲波能量轉(zhuǎn)換為機(jī)械振動(dòng) Compensates for the air - fluid impedance difference 補(bǔ)償氣液相不同媒介的導(dǎo)抗差 The

3、 Middle ear anatomy 中耳解剖中耳解剖 Air Air Air pressure must be near equal on both sides of the ear drum in order to optimise mobility of the whole system 應(yīng)使鼓膜兩側(cè)氣壓接近，從而保證中耳傳 聲系統(tǒng)的最佳活動(dòng)性 The Eustachian tube (ET) ventilates the middle ear and allows pressure equalisation 咽鼓管是中耳的通氣管道，可保證中耳氣壓平衡 The ET opens whe

4、n swallowing or yawning 吞咽和打哈欠時(shí)咽鼓管開放 Inner ear fluids 內(nèi)淋巴 Getting sound into a different medium 聲音在不同媒介中的傳導(dǎo)聲音在不同媒介中的傳導(dǎo) The “stiletto” principle:圓錐效應(yīng) Force is collected over a larger area and focused on a smaller area (B) 作用力在錐底收集后聚焦到錐尖 How do we test the middle ear? 如何檢測中耳功能如何檢測中耳功能 中耳測試中耳測試 精密的中耳系統(tǒng)

5、 高精度的測試 高質(zhì)量控制系統(tǒng) Part of the probe tone is reflected, and some is admitted into the middle ear 一部分探測音被反射回來，另一部分則進(jìn)入中耳 The admittance is continuously measured by a microphone 聲導(dǎo)納通過麥克風(fēng)持續(xù)測量計(jì)算出來 Admittance - letting the sound wave in 聲導(dǎo)納將聲波導(dǎo)入聲導(dǎo)納將聲波導(dǎo)入 鼓室圖鼓室圖 中耳 勁度 TPP ( = MEP? ) Admittance Pressure Tympano

6、metry 鼓室聲導(dǎo)抗 Admittance -200 daPa200 daPa0 Ear canal pressure Admittance 聲導(dǎo)納 -200 daPa200 daPa0 Ear canal pressure 外耳道壓強(qiáng) 1 & 3: Pressure stiffens the tympanic membrane so the probe tone bounces back, and the sound level in the middle ear decreases 1和3：大壓強(qiáng)使鼓膜僵硬從而探測音多被反彈回來，進(jìn)入中耳的聲能減少 2: When pressure is

7、 equal on both sides, the sound level in the middle ear is at maximum 2：鼓膜兩側(cè)壓力相等時(shí)傳入中耳的聲能最大 1 2 3 The Tympanogram curve, ECV and TPP 鼓室導(dǎo)抗圖形，等效外耳道容積和峰壓點(diǎn) The TPP approximates the middle ear pressure 峰壓點(diǎn)近似于鼓膜內(nèi)側(cè)的中耳壓力 ECV Total Admittance of the ear canal and the middle ear 外耳道和中耳的聲導(dǎo)納總值 TPP Pressure sweep

8、 The 226 Hz admittance of the air in the ear canal is directly proportional to the volume of that air. That gives us the Equivalent Ear Canal Volume, ECV 以226Hz為探測音，測試探頭與鼓膜之間的空氣導(dǎo)納值為外耳道容積，即等效 外耳道容積 ECV Total Admittance SA TPP SA TPP The Tympanogram curve and baseline compensation 鼓室導(dǎo)抗圖形和基線補(bǔ)償鼓室導(dǎo)抗圖形和基線

9、補(bǔ)償 Subtraction of the ECV contribution gives us a baseline compensated tympanogram 去除外耳道容積成分后的鼓室圖稱為基線補(bǔ)償鼓室導(dǎo)抗圖 Peak admittance becomes Static Admittance, SA 該圖峰值處的聲導(dǎo)納稱為靜態(tài)聲導(dǎo)納(SA) The SA is the admittance of the middle ear alone. Now we can use the normative data! SA等于中耳的聲導(dǎo)納值 -2002000 Type Ad: Ossicular

10、 discontinuity or age related hypermobility Ad型：聽骨鏈中斷或鼓膜松弛 -2002000 Type A: Normal A型：正常 -2002000 Type B: “Flat” -Effusion or perforated ear drum depending on ECV value B型：平坦型。鼓室積液或鼓膜穿孔，根據(jù)ECV值區(qū)分 -2002000 Type As: Possible effusion or otosclerosis As型：鼓室積液可能或耳硬化癥 -2002000 Type C: Abnormal pressure C型

11、：負(fù)壓型 The Tympanogram curve classification, Type 鼓室導(dǎo)抗圖形分類鼓室導(dǎo)抗圖形分類 SA TW SA/2 Pressure Admittance The Tympanogram curve and Tympanometric Width 鼓室導(dǎo)抗圖形與鼓室圖寬度（鼓室導(dǎo)抗圖形與鼓室圖寬度（TW） Tympanometric Width quantify the steepness of the tympanogram TW決定鼓 室導(dǎo)抗圖的坡度 Normative data exist for different age groups 不同年齡組標(biāo)

12、準(zhǔn)化值不同 TW and SA are the criteria used in the ASHA tympanometric screening protocol 美國社會(huì)衛(wèi)生學(xué)會(huì)的鼓室聲導(dǎo)抗篩查方案把TW和SA作為診斷指標(biāo) 226 Hz: Different configurations of tympanometric results 226Hz鼓室聲導(dǎo)抗測試結(jié)果與疾病的關(guān)系鼓室聲導(dǎo)抗測試結(jié)果與疾病的關(guān)系 Tympanometry is an invaluable diagnostic tool when combined with other audiological tests 鼓室

13、聲導(dǎo)抗與其它聽力學(xué)測試結(jié)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 The two middle ear muscles 中耳肌中耳肌 1 2 1: Tensor muscle 鼓膜張肌 2: Stapedius Muscle 鐙骨肌 The muscles are believed to stabilise the mechanical system and protect the cochlea from excessive low frequency vibration 中耳肌可穩(wěn)

14、定中耳機(jī)械系統(tǒng)，并保護(hù)耳蝸免受低頻強(qiáng)聲損傷 The Acoustic Reflex 聲反射聲反射 Loud sounds make the stapedius muscle contract.This makes the middle ear system stiffer. 強(qiáng)聲刺激可使鐙骨肌收縮，從而增加中耳傳聲系統(tǒng)的勁度 and less low frequency sound can get through the middle ear 因而進(jìn)入中耳的低頻聲波減少 Stapedius muscle controlled by facial nerve (CN VII) 鐙骨肌由第七對(duì)顱神

15、經(jīng)面神經(jīng)支配 Network in brainstem consists of ipsilateral and contralateral paths 腦干層面由同側(cè)和對(duì)側(cè)神經(jīng)通路組成 Reflex activated on both ears, even when stimulation only occurs in one ear 一側(cè)耳受到刺激時(shí)，雙側(cè)鐙骨肌都會(huì)收縮 Comparison of ipsilateral vs. contralateral acoustic reflexes helps to determine site of lesion 對(duì)比同側(cè)和對(duì)側(cè)聲反射有助于判斷病

16、變部位 The Middle ear - Immittance tests 中耳聲導(dǎo)納測試中耳聲導(dǎo)納測試 Acoustic reflex threshold 聲反射閾 聲反射聲反射 Admittance Time Deflection 0.02 蹬骨肌 0.00 0.02 80 dB HL 0.00 0.02 85 dB HL 0.00 0.02 95 dB HL 0.00 0.02 90 dB HL Deflection criterion 聲導(dǎo)納偏移標(biāo)準(zhǔn) -It is useful to study the growth with intensity to confirm a reflex

17、 threshold -繼續(xù)增加聲強(qiáng)觀察偏移變化有助于進(jìn)一步明確聲反射閾 ? ! Acoustic Reflex Thresholds 聲反射閾聲反射閾 Loud stimuli are presented, whilst the admittance is measured 強(qiáng)聲刺激出現(xiàn)時(shí)，可測試出聲導(dǎo)納值的變化 聲反射測試聲反射測試 高精度的挑戰(zhàn)高精度的挑戰(zhàn) 鼓膜處壓力為TPP值時(shí)中耳蹬骨肌反射 狀 況最佳 正確的聲反射是刺激音引起導(dǎo)納在TPP 處 的變化 耳道或中耳壓力的改變導(dǎo)致錯(cuò)誤的聲反 射 對(duì)于鼓膜活動(dòng)度過大可進(jìn)行TPP補(bǔ)償 Threshold+10 dB, 10 seconds s

18、timulus time 聲反射閾上10dB給聲，刺激時(shí)程10s 0 510 seconds Admittance change Half-Life Time (HLT), the time after stimulus onset when the admittance deflection has decreased by 50%. 半衰期是指聲反射振幅減少50的時(shí)程 A half-life time value 5 seconds is indicative of tumour 半衰期小于5秒提示蝸后病變，常見的疾病是聽神經(jīng)瘤 No reflex decay present 陰性 Adm

19、ittance change Max 50 % of Max HLT 0 510 seconds Reflex decay present!陽性 Acoustic Reflex Decay 聲反射衰減聲反射衰減 The reflex should be activated in both ears even if stimulated in only one ear 單耳刺激聲可激活雙耳聲反射 The upper normal intensity limit for reflex thresholds in adults is 95 - 100 dB HL 正常成人聲反射閾上限是95100dB

20、 HL Reflex thresholds cannot be determined if there is a problem with the middle ear 中耳疾病時(shí)不能測出聲反射閾 Broad Band Noise provokes a reflex at about 10 - 15 dB lower than pure tone stimuli 寬帶噪聲聲反射閾較純音刺激聲低1015dB Determines type of hearing loss when compared with the audiogram 聲反射閾與聽力圖比較可幫助判斷耳聾類型 Decays wit

21、h neural fatigue (typically 8th nerve tumour) 衰減提示聽神經(jīng)疲勞，是聽神經(jīng)腫瘤的典型表現(xiàn) Acoustic Reflex features 聲反射特征聲反射特征 Different configurations of Acoustic Reflex results 聲反射結(jié)果與疾病的關(guān)系聲反射結(jié)果與疾病的關(guān)系 Using this kind of table makes reflex interpretation easier 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

22、經(jīng)/右 面神經(jīng)/左 腦干/右 腦干/左 腦干/中線 226 Hz probe tone : Normal tympanogram in abnormal ear! 226Hz探測音：異常中耳顯示正常鼓室導(dǎo)抗圖 Tympanometry in infants younger than 4 - 7 months 47個(gè)月以下嬰兒的鼓室聲導(dǎo)抗個(gè)月以下嬰兒的鼓室聲導(dǎo)抗 226 Hz probe tone The infant outer and middle ears are still developing, and do not vibrate with sound the same way ad

23、ult ears do. 嬰兒外耳和中耳正處于發(fā)育期，與成人的聲波振動(dòng)方式不同 Use 1000 Hz probe tone in infants 推薦使用1KHz探測音 Tympanometry in infants 嬰兒鼓室聲導(dǎo)抗嬰兒鼓室聲導(dǎo)抗 1000 Hz tympanometry clearly indicates abnormal middle ear function! 1kHz鼓室聲導(dǎo)抗明確顯示中耳功鼓室聲導(dǎo)抗明確顯示中耳功 能異常能異常 Normal 226 Hz tympanograms for both ears! 226Hz鼓室聲導(dǎo)抗顯示雙耳正常鼓室聲導(dǎo)抗顯示雙耳正常

24、Acoustic reflexes confirm a healthy right side middle ear. 聲反射證實(shí)右側(cè)中耳功能正常聲反射證實(shí)右側(cè)中耳功能正常 How easily can I move this me chanical system? 怎樣輕而易舉的推動(dòng)這個(gè)機(jī)械系統(tǒng)？ Traditional admittance magnitude tympanometry 傳統(tǒng)鼓室聲導(dǎo)抗中聲導(dǎo)納的成分傳統(tǒng)鼓室聲導(dǎo)抗中聲導(dǎo)納的成分 B/G component tympanogram 聲納聲納/聲導(dǎo)成分鼓室導(dǎo)抗圖聲導(dǎo)成分鼓室導(dǎo)抗圖 B: Susceptance 聲納 G: Cond

25、uctance 聲導(dǎo) Now I can see not only how easily I can move the system, but I can actually find out why! 現(xiàn)在我不僅能輕而易舉的推動(dòng)它，而且還明白了其中的 原因！ Susceptance and Conductance magnitude tympanometry 聲導(dǎo)與聲納聲導(dǎo)與聲納 Traditional baseline compensation Ear canal effect at +200 daPa CCSA is not calculated through simple ECV su

26、btraction, but through compensating the B and G components individually before putting them together CCSA不是簡單減去ECV得到的，而是分別對(duì)聲導(dǎo)和聲納補(bǔ)償后再相加計(jì)算出來的 CCSA Component Compensated Static Admittance 成分補(bǔ)償聲導(dǎo)納成分補(bǔ)償聲導(dǎo)納 CCSA Middle ear assessment in infants, recommendations 嬰兒中耳評(píng)估的推薦方法嬰兒中耳評(píng)估的推薦方法 q Low frequency probe

27、tone tympanometry is unreliable in infants and should not be used 低頻探測音由于鼓室聲導(dǎo)抗測試結(jié)果不可靠，不推薦使用于嬰兒 q 1000 Hz probe tone is preferable to 678 Hz 1kHz探測音優(yōu)于678Hz q A low peak, below 1000 Hz norm data range, or no peak at all is likely due to effusion 低于1kHz正常數(shù)據(jù)范圍的低峰或無峰的測試結(jié)果提示中耳積液 q Reflex testing in infants: 嬰兒聲反射測試 1000 Hz probe tone 1kHz探測音 ipsilateral stimulation 同側(cè)刺激音 broadband noise stimulus 寬帶噪聲刺激音 q Combine 1000 Hz tympanometry and reflex testing 將1kHz鼓室聲導(dǎo)抗與聲反射測試相結(jié)合綜合判斷 鼓室圖鼓室圖 中耳 勁度 TPP ( = MEP? ) Admittance Pressure ECV Total Admittance SA TPP SA TPP The Tympanogram curve