声导抗基础知识

1、声导抗基础知识培训tympanometry and acoustic reflex measurements鼓室声导抗和声反射测试+infant test recommendations 婴儿测试的推荐方法sound travel 声音传导声音传导getting sound into a different medium声音在不同媒介中的传导声音在不同媒介中的传导most of the sound energy is reflected when confronting a another medium.大部分声能在临界面处被反射回来because different media are mo

2、re or less easy to bring into motion (impedance)因为不同媒介的声阻抗是不同的the role of the middle ear 中耳的作用中耳的作用the ossicles 听小骨听小骨malleus 锤骨incus 砧骨stapes 镫骨 three small bones forming a chain between the tympanic membrane and the inner ear听骨链位于鼓膜和内耳之间，由3块听小骨组成 airborne sound wave energy becomes mechanical vibra

3、tion空气传导的声波能量转换为机械振动 compensates for the air - fluid impedance difference补偿气液相不同媒介的导抗差the middle ear anatomy 中耳解剖中耳解剖airairair pressure must be near equal on both sides of the ear drum in order to optimise mobility of the whole system应使鼓膜两侧气压接近，从而保证中耳传声系统的最佳活动性the eustachian tube (et) ventilates the

4、 middle ear and allows pressure equalisation咽鼓管是中耳的通气管道，可保证中耳气压平衡the et opens when swallowing or yawning吞咽和打哈欠时咽鼓管开放inner ear fluids 内淋巴getting sound into a different medium声音在不同媒介中的传导声音在不同媒介中的传导the “stiletto” principle:圆锥效应force is collected over a larger areaand focused on a smaller area (b)作用力在锥底

5、收集后聚焦到锥尖how do we test the middle ear?如何检测中耳功能如何检测中耳功能中耳测试中耳测试 精密的中耳系统 高精度的测试 高质量控制系统part of the probe tone is reflected, and some is admitted into the middle ear 一部分探测音被反射回来，另一部分则进入中耳the admittance is continuously measured by a microphone 声导纳通过麦克风持续测量计算出来admittance - letting the sound wave in声导纳将声波

6、导入声导纳将声波导入鼓室图鼓室图中耳 劲度tpp ( = mep? )admittancepressuretympanometry 鼓室声导抗admittance-200 dapa200 dapa0ear canal pressureadmittance 声导纳-200 dapa200 dapa0ear canal pressure 外耳道压强1 & 3: pressure stiffens the tympanic membrane so the probe tone bounces back, and the sound level in the middle ear decrea

7、ses1和3：大压强使鼓膜僵硬从而探测音多被反弹回来，进入中耳的声能减少2: when pressure is equal on both sides, the sound level in the middle ear is at maximum2：鼓膜两侧压力相等时传入中耳的声能最大 123the tympanogram curve, ecv and tpp鼓室导抗图形，等效外耳道容积和峰压点the tpp approximates the middle ear pressure峰压点近似于鼓膜内侧的中耳压力ecvtotal admittance of the ear canal and

8、the middle ear外耳道和中耳的声导纳总值tpp pressure sweepthe 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为探测音，测试探头与鼓膜之间的空气导纳值为外耳道容积，即等效外耳道容积ecvtotal admittancesatppsatppthe tympanogram curve and baseline

9、 compensation 鼓室导抗图形和基线补偿鼓室导抗图形和基线补偿subtraction of the ecv contribution gives us a baseline compensated tympanogram 去除外耳道容积成分后的鼓室图称为基线补偿鼓室导抗图peak admittance becomes static admittance, sa该图峰值处的声导纳称为静态声导纳(sa)the sa is the admittance of the middle ear alone. now we can use the normative data!sa等于中耳的声导纳

10、值-2002000type ad: ossicular discontinuity or age related hypermobilityad型：听骨链中断或鼓膜松弛-2002000type a: normala型：正常-2002000type b: “flat” -effusion or perforated ear drum depending on ecv valueb型：平坦型。鼓室积液或鼓膜穿孔，根据ecv值区分-2002000type as: possible effusion or otosclerosisas型：鼓室积液可能或耳硬化症-2002000type c: abnor

11、mal pressurec型：负压型the tympanogram curve classification, type 鼓室导抗图形分类鼓室导抗图形分类satwsa/2pressureadmittancethe tympanogram curve and tympanometric width 鼓室导抗图形与鼓室图宽度（鼓室导抗图形与鼓室图宽度（tw）tympanometric width quantify the steepness of the tympanogram tw决定鼓室导抗图的坡度normative data exist for different age groups不同年

12、龄组标准化值不同tw and sa are the criteria used in the asha tympanometric screening protocol美国社会卫生学会的鼓室声导抗筛查方案把tw和sa作为诊断指标226 hz: different configurations of tympanometric results226hz鼓室声导抗测试结果与疾病的关系鼓室声导抗测试结果与疾病的关系tympanometry is an invaluable diagnostic tool when combined with other audiological tests鼓室声导抗

13、与其它听力学测试结合是不可替代的诊断工具疾病早期中耳积液中耳积液听骨链中断鼓膜病变耳硬化症锤骨固定咽鼓管阻塞鼓膜置管鼓膜穿孔耵聍栓塞、探头叩堵塞the two middle ear muscles 中耳肌中耳肌121: tensor muscle 鼓膜张肌2: stapedius muscle 镫骨肌the muscles are believed to stabilise the mechanical system and protect the cochlea from excessive low frequency vibration中耳肌可稳定中耳机械系统，并保护耳蜗免受低频强声损伤t

14、he acoustic reflex 声反射声反射loud sounds make the stapedius muscle contract.this makes the middle ear system stiffer.强声刺激可使镫骨肌收缩，从而增加中耳传声系统的劲度and less low frequency sound can get through the middle ear因而进入中耳的低频声波减少 stapedius muscle controlled by facial nerve (cn vii) 镫骨肌由第七对颅神经面神经支配 network in brainstem

15、 consists of ipsilateral and contralateral paths 脑干层面由同侧和对侧神经通路组成 reflex activated on both ears, even when stimulation only occurs in one ear 一侧耳受到刺激时，双侧镫骨肌都会收缩 comparison of ipsilateral vs. contralateral acoustic reflexes helps to determine site of lesion 对比同侧和对侧声反射有助于判断病变部位the middle ear - immitta

16、nce tests 中耳声导纳测试中耳声导纳测试acoustic reflex threshold 声反射阈声反射声反射admittancetimedeflection0.02蹬骨肌0.000.0280 db hl0.000.0285 db hl0.000.0295 db hl0.000.0290 db hldeflection criterion声导纳偏移标准-it is useful to study the growth with intensity to confirm a reflex threshold-继续增加声强观察偏移变化有助于进一步明确声反射阈? !acoustic ref

17、lex thresholds 声反射阈声反射阈loud stimuli are presented, whilst the admittance is measured强声刺激出现时，可测试出声导纳值的变化声反射测试声反射测试 高精度的挑战高精度的挑战 鼓膜处压力为tpp值时中耳蹬骨肌反射状 况最佳 正确的声反射是刺激音引起导纳在tpp处 的变化 耳道或中耳压力的改变导致错误的声反射 对于鼓膜活动度过大可进行tpp补偿threshold+10 db, 10 seconds stimulus time 声反射阈上10db给声，刺激时程10s0510secondsadmittance change

18、half-life time (hlt), the time after stimulus onset when the admittance deflection has decreased by 50%.半衰期是指声反射振幅减少50的时程a half-life time value 5 seconds is indicative of tumour半衰期小于5秒提示蜗后病变，常见的疾病是听神经瘤no reflex decay present 阴性admittance changemax50 % of maxhlt0510secondsreflex decay present!阳性acous

19、tic reflex decay 声反射衰减声反射衰减 the reflex should be activated in both ears even if stimulated in only one ear 单耳刺激声可激活双耳声反射 the upper normal intensity limit for reflex thresholds in adults is 95 - 100 db hl 正常成人声反射阈上限是95100db hl reflex thresholds cannot be determined if there is a problem with the midd

20、le ear 中耳疾病时不能测出声反射阈 broad band noise provokes a reflex at about 10 - 15 db lower than pure tone stimuli 宽带噪声声反射阈较纯音刺激声低1015db determines type of hearing loss when compared with the audiogram 声反射阈与听力图比较可帮助判断耳聋类型 decays with neural fatigue (typically 8th nerve tumour) 衰减提示听神经疲劳，是听神经肿瘤的典型表现 acoustic r

21、eflex features 声反射特征声反射特征different configurations of acoustic reflex results 声反射结果与疾病的关系声反射结果与疾病的关系using this kind of table makes reflex interpretation easier使用该表格有助于判断声反射的临床意义病变部位/患耳中耳/右中耳/左耳蜗/右耳蜗/左听神经/右听神经/左面神经/右面神经/左脑干/右脑干/左脑干/中线226 hz probe tone : normal tympanogram in abnormal ear!226hz探测音：异常中耳

22、显示正常鼓室导抗图tympanometry in infants younger than 4 - 7 months 47个月以下婴儿的鼓室声导抗个月以下婴儿的鼓室声导抗226 hz probe tonethe infant outer and middle ears are still developing, and do not vibrate with sound the same way adult ears do.婴儿外耳和中耳正处于发育期，与成人的声波振动方式不同use 1000 hz probe tone in infants 推荐使用1khz探测音tympanometry in

23、 infants 婴儿鼓室声导抗婴儿鼓室声导抗1000 hz tympanometry clearly indicates abnormal middle ear function!1khz鼓室声导抗明确显示中耳功鼓室声导抗明确显示中耳功能异常能异常normal 226 hz tympanograms for both ears! 226hz鼓室声导抗显示双耳正常鼓室声导抗显示双耳正常acoustic reflexes confirm a healthy right side middle ear.声反射证实右侧中耳功能正常声反射证实右侧中耳功能正常how easily can i move

24、this mechanical system?怎样轻而易举的推动这个机械系统？traditional admittance magnitude tympanometry传统鼓室声导抗中声导纳的成分传统鼓室声导抗中声导纳的成分b/g component tympanogram 声纳声纳/声导成分鼓室导抗图声导成分鼓室导抗图b: susceptance声纳g: conductance声导now i can see not only how easily i can move the system, but i can actually find out why!现在我不仅能轻而易举的推动它，而且还明白了其中的原因！susceptance and conductance magnitudetympanometry 声导与声纳声导与声纳traditional baseline compensationear canal effect at +20